Shannon McNulty, a 17-year-old wannabe doctor from Sterling, thought she might get queasy watching heart surgery, but instead she found the experience "so neat" that it may influence her career choice.

McNulty, a rising senior at Park View High School in Loudoun County, is one of 30 students--including five from Northern Virginia--who are spending the summer shadowing physicians at Virginia Commonwealth University's Medical College of Virginia here as participants in the Governor's School for Medicine.

Each of the students is assigned to a physician-mentor and, like a medical student, follows a rotation that allows the student to glimpse doctors in fields other than that of their mentors.

"They have a chance to observe surgery, childbirth and emergency medicine--experiences that many medical school students don't have until their third year," said Kirk Blackward, the program's director.

Past participants in the six-week program, now in its 11th year, have gone on to premed programs and medical schools at universities across the country. Its MCV sponsors believe the program was the only one of its kind until this summer, when one of its early graduates started a similar one at Vanderbilt University.

McNulty saw her first surgery last week, a triple-bypass of the heart by cardiac surgeon David Salter. The petite McNulty, who stood on a stool and peeked over the patient's head during the three-hour operation, saw, in addition to an exposed beating heart, black specks on the woman's lung.

"I could tell she was a smoker," McNulty recalled. "Just seeing that--I'm never smoking."

McNulty's primary mentor is cardiologist James Arrowood, who said most patients are "receptive to the students." Because they are in an academic setting, they are used to seeing a parade of medical students and residents, Arrowood said, so one more face at the bedside "doesn't make a lot of difference."

In addition to trailing doctors through the halls of the 822-bed hospital, each of the students is expected to pursue a research project, and to make a report to the group when the program ends Aug. 6.

McNulty is helping Arrowood study the causes of heart attacks in post-menopausal women.

Mark Chao, 16, from Robinson Secondary School in Fairfax County, is following a pediatric neurosurgeon and is analyzing 10 years of brain tumors in infants.

Lauren Mara Metcalfe, from Stonewall Jackson High in Prince William County, is assigned to a specialist in infectious diseases and is evaluating the correlation between hepatitis C and HIV in pediatric patients.

Jessica Stansfield, of Gar-Field High in Prince William, is tracking a neurologist and is assessing the effect of jaundice on baby rats.

Kelly Benedict, 17, from Fairfax High School, is assigned to two plastic and reconstructive surgeons and is studying the effects and possible corrections of a birth defect in which the soft spot on the skull has closed in the womb, blocking the skull and brain from normal growth after birth.

The first time Benedict witnessed a face lift, "I tried not to look too much, because I was afraid I'd be grossed out," she said. But after watching several surgeries performed by her mentors, Andrea Pozez and Isaac Wornom, Benedict said, "I like to look."

But for Benedict, a suburbanite like all the Northern Virginia students, "it's not just the medicine" that makes the program exciting. "The hospital is in the middle of the city," and the students' dormitory is just a few blocks from MCV's emergency room, one of the 15 busiest in the nation.

"I didn't know so many people in the world had AIDS," Benedict said, "but now I see one person a day" with the disease.

Chao, whose mother is a medical researcher at the National Institutes of Health in Bethesda and whose brother Dan, 20, is a premed student at VCU, said he was unsure about medicine as a career before arriving on campus June 28.

But the experience has been "inspiring. I'm doing and watching things that I only dreamed of," Chao said.

Chao has been impressed with "the compassion, the interacting with patients" he has seen by his mentor, John D. Ward.

"He's funny and intelligent, and he really loves the kids," Chao said of Ward, 54, who formed a nonprofit foundation to finance an annual trip to Guatemala, where for the last 10 years he and his team have performed dozens of operations on children in that poor country.

Chao arrived here planning a career as a laboratory scientist, but he has been so inspired by Ward that "now I'm actually thinking about neurosurgery because of him."

Although the students work a full 40-hour week and even volunteer at night for other duties, such as replenishing pills in the hospital pharmacy, there has been plenty of time for fun.

They have gone rafting and tubing on the James River, been ice skating and swing dancing, and spent a day at nearby Paramount's Kings Dominion.

Chao wound up on the receiving end of medical care recently, when he sprained his ankle playing basketball. Now, much to the teasing of his colleagues, he hobbles from patient to patient on crutches.

Because of rotating schedules, the students remain in Richmond seven days a week, but they saw their parents at a Family Day outing recently.

The Governor's School, which during the regular school year operates programs at six sites in the state for gifted students, sponsors half a dozen summer sessions, including others in the arts, humanities, science and math.

Students in the medical program were chosen by a committee that included representatives from the Governor's School, MCV and the state Department of Education. All 150 applicants needed to score in the 95th percentile on standardized tests, be recommended by a principal or counselor and offer references.