Abstract. Food restriction is known to sensitize the reproductive axis of rats to the inhibitory action of the pineal gland and its hormone, melatonin. The present study investigated the effect of pinealectomy on the undernutrition-related reproductive suppresion. Three groups of animals (control, sham pinealectomy or pinealectomy) were subjected to either 3 weeks of 50% food restriction or ad libitum feeding under a lighting regimen of 14 h light and 10 h dark. At the end of the treatment period, body weight, testes weight, accessory organ weights, serum LH and serum testosterone were determined. In the pinealectomized animals, accessory organ weights and serum testosterone levels increased significantly. As compared to the controls, underfed pinealectomized animals had a partial recovery of the reduced accessory organ weights and normalization of the serum testosterone levels. These findings suggests that pinealectomy has a protective effect on the gonads of both control and underfed animals and that underfed animals are more sensitive to this protective mechanism.