In cervical cancer, abnormalities of ras genes have not been fully investigated. We studied the expression and mutation of H-ras oncogene in cervical cancer to investigate their relationship and usefulness as an independent prognostic indicator. Twenty-seven paraffin-embedded resection specimens of cervical cancer (21 squamous, 3 adeno, 2 adenosquamous, and 1 small cell) were examined by immunohistochemistry using a mAb H-ras p21 and by PCR and allele-specific oligonucleotide hybridization using H-ras codon 12 and 61 amplimers and oligonucleotide probes. A strong immunoreaction was noted in 10 cases (37%) and weak immunoreaction in an additional 6 cases (22%). H-ras codon 12 mutations were detected in 6 of 27 cases (22%) and all of the mutations were guanine to adenine transitions. There was no mutation in codon 61. Cases with codon 12 mutations included all 3 squamous, 2 adeno, and I adenosquamous carcinoma. Only 3 of 16 (19%) cases with positive staining and 3 of 11 (27%) cases with negative staining showed mutations. No correlation was found between ras gene alterations and patient survival time. Our findings indicate that expression and mutation of H-ras oncogene occur in cervical cancer but their determination adds no useful prognostic information.