Tumor necrosis factor (TNF) alpha can induce both cell death and proliferation by binding to either TNF receptor (TNFR) 1 or 2. In the granulosa cells of porcine ovaries, TNFalpha is considered to act as an anti-apoptotic/survival factor during follicular atresia. As a first step toward elucidating the function of TNFR2 in regulating follicular development/growth and atresia in porcine ovaries, we isolated the porcine (Sus scrofa) cDNA encoding TNFR2, which was identified from a cDNA library prepared from the follicular granulosa cells of pig ovaries. Porcine TNFR2 (1,125 bp, 375 amino acid residues), which contains specific amino acid region of transmembrane, indicated high identities with human and murine TNFR2 (78 and 69% at mRNA level, respectively; 73 and 61% at protein level, respectively), suggesting that the function of porcine TNFR2 is similar to that of human and murine homologues. Understanding the expression patterns of porcine TNFR2 mRNA in various organs, which we confirmed by reverse transcription polymerase chain reaction analysis, would help to elucidate the physiological role of TNFR2 in the regulation of apoptosis in porcine organs.