Mild hyperlipidaemia induced by cholesterol feeding to male rats altered testicular histology. The sperm motility and density were significantly reduced in cauda epididymides and testes in mild hyperlipidaemic rats. The testicular cell population i.e. spermatocytes (primary and secondary) and spermatids were significantly reduced (P < or = 0.01 to 0.001). However, the number of degenerating Leydig cells (interstitial cells) were increased significantly (P < or = 0.001). Serum biochemistry reveals significant rise in cholesterol and triglycerides. It is concluded that cholesterol feeding caused inhibition of spermato genesis.