Cryptococcal infections are not reportable illnesses, and there have been limited attempts to estimate their incidence or prevalence. This study estimates the prevalence of cryptococcal disease in New York City in 1991 among human immunodeficiency virus (HIV)-infected patients who were at risk. Numerator data were generated by surveying all hospitals in New York City to determine the number of patients with cultures positive for Cryptococcus neoformans as well as the number of patients with positive cryptococcal latex agglutination tests in 1991; 517 culture-positive patients were identified, and 1,277 patients were estimated to have a positive cryptococcal latex antigen test. Of these cases, 96% were estimated to be related to infection with HIV. Denominator data were generated via an active surveillance program of the New York City Department of Health. The annual prevalence of cryptococcosis among HIV-infected patients at risk in New York City is estimated to be 6.1%-8.5%.