Human papillomavirus (HPV) types 16 and 18 have been found closely associated with squamous cell carcinoma and related lesions of the uterine cervix. In order to investigate the relationship between HPV and adenocarcinoma and adenosquamous carcinoma of the uterine cervix, formalin-fixed, paraffinembedded tissues prepared from 38 cases consisting of 30 cases of adenocarcinoma and 8 cases of adenosquamous carcinoma were examined for the presence of HPV DNA by in situ hybridization with digoxigenin labeled HPV 6/11, 16, 18 DNA probes. HPV DNA was localized on the nuclei of the cancer cells in adenocarcinoma and adenosquamous carcinoma. HPV DNA was detected in 13 cases (43.3%) of adenocarcinoma and 4 cases (50.0%) of adenosquamous carcinoma, and HPV type 18 DNA was detected in 13 cases (34.2%) of adenocarcinoma and adenosquamous carcinoma. These findings suggest an association between HPV, especially HPV type 18, and adenocarcinoma and adenosquamous carcinoma of the uterine cervix.