Donald G. Herzberg, 55, dean of the graduate school and vice president for graduate studies and research at Georgetown University, died in New York City Monday of an apparent heart attack.

He was vacationing at the time, a Georgetown spokesman said.

Mr. Herzberg was a political scientist by training and an authority on electoral politics and immigration law. He had served as a consultant to the American Broadcasting System on politics.

He was a critic of the recent reforms undertaken by the Democratic Party under which delegates to national convention must vote for the candidates they represented in the primaries.

"In the name of reforming political parties we are destroying them," he once said. "Wheeling and dealing, compromising and trading are preferable to hyped-up primaries and confusing caucuses."

Mr. Herzberg returned from Thailand last week from a survey of the work being done there by Georgetown students at the Nong Khai refugee camp. He was a founder of the Georgetown Center for Immigration Policy and had served on the Select Commission on Western Hemisphere Immigration. He also has served on President Kennedy's Commission on Registration and Voting Participation.

Mr. Herzberg was born in Orange, N.J. He graduated from Wesleyan Univeristy in 1946 and did graduate work at Syracuse University.

He was a special assistant to the comptroller of Connecticut from 1949 to 1951 and then served as legislative assistant to Sen. William Benton (D-Conn.). He was a budget official in the State of New York in 1955 and 1956.

Mr. Herzberg began his academic career in 1956 when he was named executive director of the Eagleton Institute of Politics at Rutgers University.

He was named professor of government at Georgetown in 1973. He became dean of the graduate school in the same year. He was named a vice president of the university in 1979.

Mr. Herzberg was a member of the American Political Science Association, the American Association for the Advancement of Science and the American Federation of Radio and Television Actors. He was a former member of the board of directors of Mount Vernon College.

His publications include "Strengthening the States: Essays on Legislative Reform" and "A Student Guide to Campaign Politics."

Mr. Herzberg's survivors include his wife, Barbara, of Washington, where Mr. Herzberg lived, and five children, John of Geneva, Switzerland, Joan of Amherst, Mass., Timothy, of Stowe, Vt., Melissa, of Ontario, and Andrew, of Quebec.