Chester Marks had looked forward eagerly to retirement from his job as a research analyst for the Department of Defense.

He and his wife Laura planned to "follow the sun for a year in a motor home, find the place we liked the most and resettle there," said the Beltville resident.

In the back of Marks' mind, the fantasy still lingers. But it now is so far removed from his everyday reality that the fantasy is fading fast, he adds regretfully.

His deep brown eyes grow serious as Marks, 50, and now retired, gazes at the blood-filled tubing coiled snake-like on his lap.

"This is my life now," he says.

Marks actually considers himself lucky: His kidneys do not fail until 11 years after the organs intially were damaged when he suffered a severe strep throat.

According to Dr. Mark Rosen, medical director of the dialysis unit at Holy Cross Hospital in Silver Spring, certain antibodies the body produces to fight streptococcus infections attack the kidneys, in rare instances resulting in progressive damage.

Today, Marks is one of an estimated 320 Montgomery and Prince George's residents who rely on dialysis machines to keep them alive. The machine filters waste products from their blood, a vital life-maintaining function that no longer can be performed by their own kidneys.

Four and a half hours each Monday and Friday, Marks is connected to a dialysis machine -- his proverbial life-line.

Accepting the fact "that my longevity is not something we can depend on now," Marks encouraged his wife to return to school and try to expand her hobby -- painting -- into a career.

For Marks, the January opening of a kidney dialysis unit at Holy Cross Hospital in Silver Spring made life a little easier.

It takes Marks and his wife a total of 30 minutes to travel to Holy Cross and home again, compared with the two-hour round trip through heavy traffic to the privately run Bethesda dialysis center where he previously was treated.

The unit is the first nonprofit, hospital-based facility to open in Montgomery County. It has six machines that enable 36 patients to be cared for on three shifts per day, six days per week.

Hospital spokesman Tom Burke said the unit already is operating at full capacity and has a waiting list of new patients.

Burke admits the unit already was "out of date" in terms of capacity when it opened. Federal and state health-planning guidelines, he said, limit the number of machines available in any local jurisdiction. A hospital request for three additional machines was denied by the state health planning board last week.

About 25 new patients with chronic kidney failure are added each year to the roll of those already receiving dialysis, Burke said.

In addition to the machines at Holy Cross Hospital, there are another 31 in Montgomery County, at Bio-Medical Applications of Washington in Bethesda, and three at Shady Grove Dialysis Center in Gaithersburg. Both are privately run facilities. In Prince George's County, kidney patients receive dialysis at the Mid Atlantic Nephrology Centers in Camp Springs and Laurel, which together have 33 machines, and at Doctors Hospital in Lanham, which has three machines.

In 1972, the federal Medicare program was expanded to cover dialysis for kidney patients. The government pays a maximum of $138 per treatment.

Before federal aid was available, kidney dialysis usually was reserved for the rich. "Everyone else was left to die," said Rosen.

Rosen, who also maintains a private medical practice in Silver Spring, said the Holy Cross Hospital dialysis unit, unlike private facilities, permits all private nephrologists (kidney specialists) to monitor their own patients.

The unit's relatively small size permits staff and patients to "grow together like a family," said Joyce Villareal, the unit's head nurse, which she said is a plus for these patients who spend long hours connected to the machines. The unit staff includes nine nurses, three technicians, a social worker and a dietician. It is on the lower level of the hospital, and has a separate room where patients are trained to dialyze themselves at home.

According to Rosen, dialysis is at present the best means of supporting chronically ill patients who are not well enough to receive kidney transplants. c

Although the machines sustain life, they don't replace all the kidney's functions, Rosen said.

He predicts the dialysis machine slowly will be phased out as researchers develop better means of preventing the body from rejecting a transplanted kidney.

The major cause of chronic renal failure is yet unknown, Rosen said. Known cause include uncontrolled hypertension and diabetes. He said patients with kidney problems often complain of fatigue, nausea, a metallic taste in the mouth and difficulty with their memory -- "a feeling of walking in a daze."

Marks said his treatments are almost painless. For a short time after he is on the machine, "I feel a bit washed out," he said, adding with a large grin, "Pardon the pun."