Exercise is known to potentially affect the eating patterns. In the present study, the effect of treadmill exercise on the expressions of nitric oxide synthase (NOS) and neuronal nitric oxide synthase (nNOS) in the paraventricular nucleus (PVN) of food-deprived rats was investigated using nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry and nNOS immunohistochemistry. The present results showed that food deprivation increased NOS and nNOS expressions in the PVN of the hypothalamus and treadmill exercise suppressed food deprivation-induced enhancing of NOS and nNOS expressions in the PVN. The most suppressive effect of treadmill exercise on the expressions of NOS and nNOS were observed in the heavy-intensity exercise group. Based on the present study, it is possible that treadmill exercise alleviates desire for food under food-deprivation conditions via modulation of NOS expression.