This report summarizes results of surveillance for the acquired immune deficiency syndrome (AIDS) in the United States by the Centers for Disease Control through the first quarter of 1983. Surveillance has been predominantly passive, supplemented by active follow-up of requests to the Centers for Disease Control for pentamidine isethionate for treatment of Pneumocystis carinii pneumonia. The 1,299 reported cases showed trends of increasing incidence among all risk groups: homosexual men (72 percent), intravenous drug abusers (17 percent), persons of Haitian origin (5 percent), persons with hemophilia (1 percent), and others (6 percent). Cases were reported among residents of 35 states and the District of Columbia, with the majority from New York (49 percent) and California (22 percent). Of the 6 percent of patients without well-established risk factors for AIDS, many have suspected risk factors (e.g., blood transfusion or a sexual partner in a high-risk group).