Human papillomavirus infection currently is accepted as a major factor in the etiology of carcinoma of the cervix, vagina and vulva. While the nature of genital human papillomavirus infection in women is well documented, detailed knowledge of the disease in the male partners is lacking. Therefore, a prospective study was done to define the disease in the genitals of heterosexual men and to formulate an appropriate plan of management. We studied 52 men during an 8-month period for evidence of genital human papillomavirus infection. The majority of the lesions occurred on the shaft of the penis and on the foreskin of uncircumcised men. Deoxyribonucleic acid dot hybridization of biopsies of macroscopic warts and suspected warty lesions with mixed human papillomavirus types 6 and/or 11 and 16 and/or 18 probes revealed that 87 and 55 per cent, respectively, were positive for 1 or more of these human papillomavirus types. Of the macroscopic warts and subclinical lesions 52 and 29 per cent, respectively, contained the more potentially oncogenic types 16 and/or 18, either alone or in combination with types 6 and/or 11. There was no evidence of human papillomavirus in any semen or urine sample but human papillomavirus deoxyribonucleic acid sequences were detected in 31 per cent of the biopsies from apparently normal penile skin and in 18 per cent of the urethral mucosal biopsies. We suggest that management of human papillomavirus infection be directed toward prevention and contact screening, together with ablation of localized lesions.