An in situ hybridization technique was applied under stringent conditions to paraffin sections of urethral condylomata from male patients to determine the presence of DNA sequences of human papillomavirus (HPV) types 6, 11, 16, and 18. The material consisted of 15 classical condylomata acuminata, two flat condylomata, and five recurrent lesions. HPV DNA sequences could be identified in all 15 condylomata acuminata; in 13 lesions, two types of viral DNA were observed (types 6 and 11 in 12, types 6 and 18 in one). In the remaining two condylomata acuminata, only HPV type 11 was present. One of the two flat condylomata was negative with all the probes, and one was borderline-positive for HPV 6. Four of five recurrent lesions contained the same types of viral DNA as the primary lesions, albeit with slight differences in the intensity of viral expression. One lesion was negative with all probes. We conclude that urethral condylomata in males contain the same types of HPV as seen in other anogenital lesions of both sexes and that infection with two viral types is common. In situ hybridization with HPV DNA probes is applicable to archival material and therefore may prove to be of value in future epidemiologic studies comparing lesions in sexual partners. The determination of viral type may have therapeutic implications.