We have described in the male green frog,Rana esculenta, modifications in the total lipids and protein of the testis, fat body, liver and plasma throughout the year. We have considered 1) the fat bodies as the main deposit for lipids in the body because the lipid concentration in this organ constitutes at times more than 50% of the wet tissue, and 2) the liver as the main centre for lipid synthesis. The lipids are released in the plasma and subsequently incorporated in the fat body and in the testis. Annual changes in these parameters have been correlated with gametogenetic activity. We have emphasized the importance of the fat body in controlling testicular activity and the implications of hormones and environmental cues.