Monk, M. (Dept. of Community and Preventive Medicine, New York Medical College, Flower and Fifth Avenue Hospitals, Fifth Avenue at 106th Street. New York, N.Y. 10029) and M. E. Warshauer. Completed and attempted suicide in three ethnic groups. Am J Epidemiol 100:333–345, 1974.—By a search of medical examiner's records and hospital emergency room and admission records, completed and attempted suicide rates were determined for Puerto Ricans, other whites (hereafter, whites) and blacks living in an area of Manhattan. Puerto Rican men had the highest rates of completed suicide of all groups and Puerto Ricans, both men and women, attempted suicide two to three times more often than either blacks or whites. White women had rates for completed suicide as high as those for white men and three times as high as for black women. Otherwise, whites had rates of completed and attempted suicide only slightly higher than blacks. When whites and Puerto Ricans were combined, their rates for both completed and attempted suicide were substantially higher than the rates for blacks. It is suggested that part of the difference between white and black suicide rates reported elsewhere may reflect differential reporting or classification of deaths for the two groups. In this study, the use of information from medical examiner records resulted in higher rates than usually reported and a very small difference between white and black men. The high rates for white women resulted partly from the inclusion of deaths from barbiturate ingestion that had originally been classified as “undetermined.” The high attempted rates for Puerto Ricans remain unexplained although migration and economic conditions may play a part.