We have taken advantage of conserved regions of cDNA sequences for interferon-gamma (IFN-gamma) from other species to design polymerase chain reaction (PCR) primers capable of amplifying the protein-coding region of the canine mRNA. We report here the cDNA cloning of this region from dog lymphocytes and the cDNA sequence. The predicted amino acid sequence is also reported and compared to the known sequences of these other species. The molecular clone for the canine IFN-gamma will allow direct study of this important cytokine's role in graft rejection in the widely used experimental canine transplant model.