Margaret Beitia, 57, a registered nurse who had worked at Georgetown University Hospital for the past 15 years, died of cancer Tuesday at Sibley Memorial Hospital.

A specialist in orthopedics, she earlier had worked at Sibley and at the old Emergency Hospital here.

Mrs. Beitia was born in Pomeroy, Northern Ireland. She trained as a nurse at the Royal Waterloo Hospital in London.

She met her husband, Pedro Beitia, an exile from Spain, in England during World War II. They were married in Paris.

Mrs. Beitia worked at the American Hospital in Paris until 1952, when she and her husband came here. He was a translator with the World Health Organization and then the World Bank. He returned to San Sebastian, Spain, two years ago.

Mrs. Beitia had been active in the International Visitors Information Service here.

In addition to her husband, she is survived by a daughter, Miren E., of the home in Washington; two brothers, Patrick Harte, of Pomeroy, and Peter Harte, of London, and three sisters, Mary Markiewicz, of London, Rose Hunter, of Lisburn, Northern Ireland, and Sister Chanel, of South Africa.

The family suggests that expressions of sympathy be in the form of contributions to the American Cancer Society.