The black share of enrollment in the nation's undergraduate law, medical and graduate schools has begun to drop after almost a decade of dramatic increase, according to two studies released yesterday.

While the actual number of blacks attending colleges and universities continues to rise, their share of total enrollment in the nation's largest undergraduate universities has dropped from 8.4 per cent in 1972 to 7.3 per cent last fall.

The percentage drop has been even more pronounced in some professional schools which have dramatically in recent years.

Blacks and other minorities, for example, made up 9 per cent of the class entering the nation's medical schools this fall, down from 10 per cent in the fall of 1974. This is despite numerous special admissions programs that made it possible for 41 per cent of blacks and 52 per cent of Hispanies who applied for medical school to be admitted while only 37 per cent of white males were admitted.

In addition, the percentage of graduate degrees in business and management awarded to blacks dropped from 3.8 per cent in 1973 to 3.2 per cent.

These figures were included in studies released by the Carnegie Council on Policy Studies in Higher Education and the National Association of State Universities and Land Grand Colleges.

They came one week before the U.S. Supreme Court is scheduled to hear arguments on a controversial "reverse discrimination" case involving Allen Bakke a white student denied admission to the medical school at the University of California at Davis. Bakke alleges that a number of less qualified blacks, Hispanics and Asian-Americans were admitted ahead of him under a quota system.

The figures from the Carnegie council, a prestigious group in the higher education establishment, were included in a report on selective admissions. The report declared that "rece is relevant" in picking what students should be admitted to professional and graduate schools, but cautioned against using race as the only criterion.

Sounding remarkably similiar to a brief filed by the Justice Department in the Bakke case, the council said it favors racial goals, but not rigid quotas. It proposed a two-stage administrations process.

The first step would set up a pool of all applicants who have "a reasonable chance of success in completing the course work without reducing academic or professional standards."

Racial or ethnic background would be applied in the second step, but only if the student: had personally overcome some educational disadvantage; had been victim of racial discrimination; would bring a cultural experience to the class that it otherwise lacked; or planned to work in some underserved area, like a big city ghetta.

Dr. Clark Kerr, council president said black or Spanish-surnamed applicants from wealthy or culturally sophisticated families should not be given special treatment "Higher education should be looking at where people started, and how far they've come from where they started." he said.

The Carnegie report also offered the most complete picture to date of minority enrollment on campus. It said minority made up only 3 per cent of the enrollment is the nation's medical schools in 1968, but this jumped to 10 per cent in 1974, before dropping to 9 per cent the last two years.

The black share of law school enrollment similarly jumped from 4.3 per cent in the fall of 1969 to 8.2 per cent last fall. But the number of blacks entering law school has not changed significantly since 1972, and 17 per cent of blacks admitted to law school drop out, while 10 per cent of all students do.

In additional, only 2.9 per cent of the doctorates awarded in the nation went to American blacks in 1973-74, and almost two-thirds of those were doctorates in one field - education.