In a woman with cervical cancer and a distant lesion, the histologic distinction of metastatic cervical cancer versus another primary tumor or metastases from another cancer can be difficult and has important clinical implications. Criteria for inclusion in the study were a history of primary cervical cancer and a new lesion in which the pathologic differential diagnosis was metastatic cervical cancer versus new primary versus metastatic ovarian carcinoma. Ten cases were identified. The cervical cancers and the other lesion(s) were tested for human papillomavirus DNA by in situ hybridization and human papillomavirus RNA (E6/E7) by reverse transcriptase in situ polymerase chain reaction. Human papillomavirus DNA was detected in the primary cervical cancer by in situ hybridization in five of nine cases; viral RNA was detected by reverse transcriptase in situ polymerase chain reaction in nine of nine cases (one case was not available for viral testing). In six cases, human papillomavirus was detected in the subsequent lesion (three lung, one cervical lymph node, two retroperitoneum), documenting the latter was metastatic cervical cancer. Human papillomavirus was not detected in the other four cases (two lung, two retroperitoneum in women with ovarian cancer), documenting that they were either primary lung cancers or metastatic ovarian cancers, respectively. Reverse transcriptase in situ polymerase chain reaction for human papillomavirus RNA is a reliable method to differentiate metastatic cervical carcinoma from either a new primary tumor or a metastasis from another cancer.