In a recent study it has been shown that human papillomavirus (HPV) infection was threefold more prevalent in spontaneous abortion specimens compared with elective specimens (60% [15 of 25] v 20% [3 of 15], respectively) as analyzed by broad-spectrum HPV polymerase chain reaction (PCR) amplification and dot-blot hybridization with an HPV-16 probe. In this study, archival paraffin-embedded tissue from a subset of previously analyzed spontaneous abortion cases were reanalyzed by in situ PCR amplification so that the specific cells infected by HPV could be identified. In the current study, using a new PCR primer set for HPV-16 E6, the status of six previously analyzed cases were verified (five HPV-positive and one negative). Furthermore, syncytiotrophoblasts were identified as the predominant cellular target of HPV (HPV-16 or a related type). Finally, four of four third-trimester placentas similarly analyzed gave no HPV-positive signal. Trophoblasts are the cell type that maintains placental contact with maternal tissue and through which nutrient exchange occurs. This knowledge prompts the hypothesis that HPV-infected trophoblasts may have altered characteristics, which may lead to a compromised gestation.