In situ hybridization technique was applied using a tritiated (3H) bovine IFNG cDNA probe to regionally localize the gene on river and swamp buffalo chromosomes. The hybridization signals peaked on the 4q23→q26 bands in river buffaloes and on the Ip24→p26 bands in swamp buffaloes. The results are compared to the localization of the same gene in cattle. Possible evolutionary conservation in the Bovidae is discussed.