Concha G. Paddack, 71, a retired assistant professor of Spanish at Georgetown University, died Wednesday in San Juan, Puerto Rico, after suffering a heart attack while visiting relatives.

She retired in 1968 after 18 years with the university's School of Languages and Linguistics.

In addition to teaching Spanish, Mrs. Paddack served as a student adviser, wrote and corrected language tests for the graduate school, translated medical papers and letters for the Medical School and wrote and recorded language tapes for the Spanish department.

In the early 1950s, she also was an interpreter for international organizations and translated manual and documents from England to Spanish for the Department of Health, Education and Welfare, the Supreme Court and the World Health Organization.

Born in Manati, Puerto Rico, Mrs. Paddack was a graduate of Sacred Heart College in Cincinnati. She was a script writer and broadcaster to Latin America for radio station WLWO in Cincinnati, and lectured on Latin American art for the Cincinnati Art Museum. She came to Washington in 1950.

She is survived by her husband, George Murray Paddack, of the home in Washington; four children, John, of Lima, Peru, and Dr. Charles, Stephen, and Cornellia, all of Washington, and nine grandchildren.