Georgetown University Medical School, which already charges more for a medical education than any other school in the nation, is raising its tuition 8 percent to $13,500.

This means a medical student at Georgetown will spend $814 more for one year of schooling than the median income earned by an American family in 1976.

According to Dr. John C. Rose, dean of the private madical school, about half the students at Georgetown finance their education by joining the armed forces or U.S. Public Health Service, which require that a student give a year of service in exchange for each year's tuition received. Rose said Georgetown has more students in such programs than any other medical school in the contry.

Rose said the tuition increase, effective in September, was approved Thursday afternoon by Georgetown University's board of trustees "because we haven't had an increase in two years and costs have gone up for medical schools. Costs have increased beyond the percentage we're raising tuition."

Each student will pay $1,000 more tuition next year, Rose said.

One of the reasons Georgetown charges such high fees, said Rose, is that the District of Cloumbia dies not provide any state aid to medical schools. "Most medical schools around the nation get aid from their state legislatures," he said.

Until the fall of 1976, the federal government provided Georgetown and George Washington University medical schools with special grants of $5,000 per student in lieu of state aid to help keep tuition costs down. At that time, freshmen medical students at Georgetown were paying $5,000 tuition.

George Washington University, which raised its tuition last year on a staggered basis, will charge entering freshmen and sophomores $11,800 this fall, while juniors will pay 9,600 and seniors will pay $8,100.

The increase at Georgetown -- seniors there will pay $13,000 with other classes paying $13,500 -- is part of a national trend, according to Charles B. Fentress, spokesman for the American Association of Medical Colleges.

According to Fentress, the average tuition charged by private medical schools this past fall was $6,000, while state residents at public schools were charged $1,600.

The Carter administration has asked Congress to end the present system of federal aid which provides all medical schools with $1,000 for each student, Rose said.

According to Fentress," "we're going to see a whole rash" of tuition increases in the near future. The AAMC predicts 100 percent tuition increases at state schools and 25 percent increases at private schools.

Although Georgetown University's Rose attributes the school's high tuition to lack of state aid in the District, some medical schools tht receive little or no state aid charge much lower tuition.

Johns Hopkins University Medical School for example, receives aid from the state of Maryland -- $394.79 per student -- and its tuition this fall will be 38.8 percent the amount charged at Georgetown. Only one to two percent of its students are in Public Health Service or military programs, according to school officials.

Harvard University Medical School, which receives no student aid from the state of Massachusetts, is raising its tuition 13 percent in the fall to $6,500 -- 48 percent of Georgetown's fee.

Mitchell Adams dean for finance at Harvard, explained that school's in crease by saying "we have a number of unusual circumstances here, some financial pressures. We've had a loss of income and some extraordinary expenses, and as a result we felt we had to raise tuition."

One difference between Georgetown and medical schools like Hopkins and Harvard is the size of its endowment, the capital investment fund from which a school draws imcome to help subsidize the cost of education.

Johns Hopkins has a medical school endowment of about $70 million, from which it derives about $3 million a year in income a spoesman said. Harvard University has a total endowment of over $1 billion. A spokesman said the medical school's endowment constitutes a "good percentage" of the total investment fund.

Georgetown, however, has a medical school endowment of $3 million, from which, Rose said, it earns about $250,000 a year.

With just over 800 medical students, Georgetown is one of the largest medical schools in the country.