Thirty cases of skin warts from the Dermatology Clinic at Tri-Service General Hospital were analyzed for the presence of human papillomavirus type 1 sequences by Southern blot hybridization. Thirteen of the 30 cases were HPV-1 positive. The prevalence was 43%. Episomal HPV-1 sequences were detected in 11 of 13 HPV-1 positive cases. There are two cases which probably contained integrated forms, one contained the higher molecular weight bands, and the other with 6 kb viral genome may be the result of rearrangement and deletion. Histological studies from HPV-1 positive specimens also indicated the typical features of HPV infection. Some cases with high copy number had a high frequency of inclusion bodies. Chi-square analysis showed that HPV-1 prevalence is not related to sex and different lesion locations, but the prevalence of HPV-1 in recurrent lesions is higher than that of initial lesions.