Inhibin, a 10.7 kD FSH (follicle-stimulating hormone) suppressing prostatic peptide has been shown to be synthesized and localized in stomach specimen of monkey. In vitro incorporation of labelled amino acid (3H-leucine) into inhibin followed by specific immunoprecipitation by antiserum to inhibin demonstrated an in vitro de novo biosynthesis of inhibin by monkey stomach. Moreover, the synthesis of inhibin was found to be maximum in fundic zone of gastric mucosa compared to cardiac and antral zone. This was supported by immunohistochemical study of three anatomically different regions, especially wherein fundic zone showed intense positive staining for inhibin. Furthermore, the above data was supplemented by quantitative study of tissue inhibin content by RIA which revealed that the fundic zone of gastric mucosa has a much higher concentration of inhibin than cardiac and antral region. The relationship of zonal concentration of inhibin to gastric anatomy appears to be a noteworthy observation and may serve as an useful tool in our understanding of gastric metabolism and activity.