The epidemiology of genital white piedra was investigated in 166 young men with a variety of genital complaints. Trichosporon beigelii was isolated from sixty-six (40%) of the cultured scrotal hairs. Infection was more common among black patients--54% of those examined, compared to 16% of white patients and 30% of "others" (p less than 0.001). There was no relationship between infection and foreign travel. White piedra was also found in young women, but less frequently than in young men (14% vs 40%, respectively). Transmission rarely occurred from person to person. Occasionally multiple body sites were simultaneously infected. A relationship may exist between T. beigelii and Corynebacterium concurrently infecting genital hair shafts. Eradication of infection was extremely difficult, despite in vitro sensitivity to antifungal agents. Spontaneous remissions occurred, however, in some patients.