One of the many roles of tumor necrosis factor (TNF)-α is to control mammalian corpus luteum (CL) PG synthesis and apoptotic cell death. Here, the cellular localization of TNF-α and its type I (TNF-RI) and type II (TNF-RII) receptors in bovine luteal tissue were analyzed using in situ hybridization, immunohistochemistry, and quantitative real-time PCR. Transcripts for TNF-α were expressed in bovine CL throughout the estrous cycle, but were significantly more abundant (P < 0.01) at the regressed luteal stage than at the other stages. Localization of TNF-α transcripts and protein were observed in large and small bovine luteal cells, as well as in immune cells. Moreover, transcripts for TNF-RI and TNF-RII were expressed in bovine CL throughout the estrous cycle. The abundance of TNF-RII transcripts was greater (P < 0.01) at the regressed luteal stage than at the other stages, whereas TNF-RI transcript abundance did not significantly change. Expression of TNF-RI and TNF-RII transcripts and proteins were observed in both the large and small luteal cells, and the proteins were also expressed in the immune cells and vascular endothelial cells. These results suggest that TNF-α sources include immune cells, as well as large and small luteal cells, and that TNF-RI and TNF-RII are present in the luteal cells of the bovine CL.