Nitric oxide (NO) may be an intercellular modulator within the central nervous system. L-arginine, which results in NO synthesis, increased food intake in mice while the inhibitor of NO synthesis, L-NG-nitro arginine (L-NO Arg) inhibited food intake in food deprived mice. L-arginine, but not D-arginine, partially reversed the inhibitory effect of L-NO Arg on food intake. These findings suggest the possibility that NO may be a physiological modulator of food intake and that the possibility of exploring the utility of L-NO arg in the treatment of obesity should be explored.