In a prospective longitudinal study of 89 men with HIV infection and persistent generalized lymphadenopathy (PGL) we tried to find clinical signs predictive of development to AIDS/opportunistic infection (OI). The mean observation time was 47 months. 27 patients (30%) developed AIDS/OI after a mean of 37 months. The estimated median time from diagnosis of PGL to AIDS/OI was 68 months. Four clinical signs of progression towards AIDS/OI were identified: dermatitis of the face, yellow toe nail changes, hairy leukoplakia and oral candidiasis. One or more of these signs were recorded in 25/27 (93%) of the patients before the development of AIDS/OI. The estimated median time from registration of each sign to AIDS/OI was: dermatitis of the face, 29 months; yellow toe nail changes, 21 months; hairy leukoplakia, 18 months; and oral candidiasis, 10 months. The estimated median time from herpes zoster to AIDS was only slightly shorter than the estimated time from diagnosis of PGL to AIDS/OI.