Sue Rouch gave Rick Sirak a new life today.

She lay unconscious on her right side in Operating Room 17 in the University of Maryland Medical Center, and as a radio quietly played top hits and traffic reports, she let a young surgeon slice into her belly and withdraw her left kidney.

She allowed it to be carried in a basin of sterilized slush next door to Operating Room 6, where Sirak lay unconscious, his eyes taped closed, where it was cleaned and flushed and then carefully sutured into his opened abdomen.

Rouch wanted this done, though she had never laid eyes on Sirak before Wednesday, because he was sick and she was not, and because she had two healthy kidneys and he had none. It was that simple, really.

"It's a gift," she had said the night before the surgery. "I'm a generous person, and giving and receiving is all part of the same circle of life."

From his hotel room Thursday night, Sirak said: "It's the ultimate gift. It's like starting life all over again."

The story of Rouch, a 60-year-old mother of three from Bowie, and Sirak, a 51-year-old father from California, is a rare one.

So-called good Samaritan organ donations, in which the donor offers an organ to a recipient who is a complete stranger, are unusual. Today's was the first at the university medical center, one of the busiest kidney transplant centers in the world, where hundreds of transplants are done each year.

And Kevin Sparkman, a spokesman for the Philadelphia-based Gift of Life Donor Program, the largest organ donor program in the country, said he has heard of only a handful in the last year or so. Most live organ donors are relatives or friends of the recipient, hospital officials said, and about half of the kidneys transplanted at the medical center come from the deceased.

But good Samaritan donations may be increasing. Stephen Bartlett, the head of the hospital's division of transplantation and the man who installed Sirak's new kidney today, said the hospital is evaluating eight more such prospective donors.

And the less invasive laparoscopic surgical technique, which was used to remove Rouch's kidney today, makes it easier for donors because four small incisions are made instead of one large one.

Generosity such as Rouch's, though, remains so scarce that doctors are careful to make absolutely sure the donor's motives are pure and well thought out. "It's an irrevocable operation," said Eugene Cho, the surgeon who removed her kidney today. "Once we do this, you can never make them the same again."

As for Rouch, Cho said, "it's a tremendous, tremendous thing that she's doing."

She said the idea began with newspaper articles.

Last summer, she said in an interview Thursday night, she read two articles in The Washington Post about organ transplants and the desperate need for donors.

The first, which she read in June, "just resonated with me," she said. "This is something I'm supposed to be doing," she said she thought. "This is something I want to do. . . . I knew that it was something that was meant to be."

A native of Southborough, Mass., with a strong New England accent, Rouch is a retired secretary with a husband and three grown children who has lived in the same Cape Cod house in Bowie for 32 years. She is a chronic volunteer and blood donor--as was her father, "a very civic-minded person"--and inveterate litter hound.

Rouch said she began calling local hospitals, offering to become a donor. "They all said, 'We have no protocols for this. If you want to, go find yourself a recipient and come back and talk to us.' "

"I was not inclined to be going out and acknowledging to the world that I have a good kidney," she said. She let the matter drop. But a month later when she saw the second article, she called The Post, was put in touch with the medical center's transplant program and began a series of rigorous physical and psychological examinations.

Sirak, a direct marketing consultant, from Tarzana, a suburb of Los Angeles, came to Operating Room 6 via a vastly different route.

It began one day in the early 1960s when he, a senior in high school, and a friend were headed to the beach at Malibu along a winding mountain road in his friend's green Triumph sports car. Suddenly the car hit gravel, slid off the road and tumbled down a 75-foot cliff, coming down on top of Sirak.

While his friend was only scratched, Sirak suffered massive internal injuries and barely survived. He lived, but with one kidney destroyed and the other damaged. For 30 years, however, he managed to get by on one damaged kidney. He married, and he and his wife, Lilly, had a son. He had some minor medical problems but generally fared well.

Until 1996. In October of that year, while he was on a lengthy business assignment in Columbia, Md., his second kidney failed. He said he drove himself to a Howard County hospital and reported that he thought he had a bad cold. No, he said they told him, "it's more than that."

With no kidney function, Sirak said, he entered the world of kidney dialysis, in which patients report to a dialysis center several times a week to have their blood mechanically cleansed of impurities. "I can tell you the exact date: October 16, 1996. Three years and 25 days ago."

He said he underwent dialysis four times a week, for five hours each time, as the machine recirculated his blood 450 times an hour. It got most but not all of the impurities, and the needles they used were as thick as McDonald's straws.

"I equate it to being a piece of clothing going through the laundry," he said. "It's a very draining process. It's a rejuvenating process, but it drains you."

He likened being chained to dialysis to being in a prison halfway house.

"I'd get out of prison every other day to go home," he said. "But it takes a toll on you both physically and mentally. You have to be back in that [dialysis] chair."

Sirak became a transplant candidate almost immediately. At first, in what seemed a tremendous stroke of luck, it appeared that his wife would be a compatible donor. But the couple's hopes were crushed when she was found to have a rare inherited hepatitis that eliminated her as a donor.

"My wife was devastated," he said.

Then their long wait began, with the odds growing against Sirak's long-term survival with each year that passed.

In September, the University of Maryland Medical Center, which had Sirak on its kidney waiting list, telephoned to alert him that he had risen to No. 2 on the list. He tried not to get his hopes up, fearing another letdown.

Then Nov. 4, the center called again: "We're ready to go. When can you be here?" They had a donor. She was alive. And she was a total stranger.

"I was amazed at the concept of a strange person donating a kidney," he said. "I think I was just overwhelmed. It seemed too good to be true."

But it wasn't. Rouch had passed all her tests. She was healthy, and so were her kidneys. Her blood type and other factors were compatible with Sirak's. She would also pass the final psychiatric test. She was eager. Everything was ready.

The bills would be paid by the kidney recipient's insurance, according to the hospital.

With a send-off from the pastor of his church, Sirak took a red-eye flight from California and arrived in Baltimore on Wednesday. He then underwent a battery of tests, which he passed. And the operation--which both would weather easily--was scheduled.

At one point, he was ushered in to meet Rouch for the first time. Both were embarrassed and moved. They embraced and wept. "Am I what you expected?" Sirak asked. "Am I what YOU expected?" she asked, laughing.

Neither got much sleep Thursday night. "I heard the clock chiming quite a few of the different hours," she said.

Sirak said he had set his alarm clock, requested a wake-up call from the hotel operator and tipped a bellhop to come and knock on his door just in case. None of it was needed. He was awake all night.

About an hour before surgery, they met again in the room where Sirak was waiting. They were edgy, like boxers waiting for their bouts, parched from their preoperative fast and clothed in skimpy, hospital gowns: he in blue, she in yellow.

Rouch introduced Sirak to her husband, Duane. "Things are going to go very smoothly, I'm sure," she said. "Take my kidney and take good care of it."

He'd had his last dialysis treatment Thursday morning. "I promise," he replied.

A little after 7 today, they came for Rouch. She hugged Sirak. "We'll be okay," she said. "We're in good hands." She climbed on the gurney and was wheeled off with a wink and a wave.

Two hours later, they lay anesthetized in the adjacent operating rooms, their bodies opened, their heart monitors beeping in delicate concert.

At 9:31 a.m., Cho pulled the glistening purple organ from Rouch's incision, placed it in the metal basin and carried it, covered with a green cloth, to where Sirak waited next door.

Shortly, Bartlett began to stitch it into place.

Sue Rouch's gift had been given.