Previously it has been shown that single episode of 2 hours restraint produced anxiety and other behavioral deficits in rats. In view of a role of neem leaves and also of 5-hydroxytryptamine (5-HT) in anxiety the present study concerns effects of neem leaves extract on the synthesis of 5-HT in rat brain. Neem leaf extract (10 g/100 mi of water) at a dose of 1 ml/kg was injected to rats for 6 days. Open field activity was monitored after 3 days administration on the 4th day. The animals were restrained for 2 hours on the 5th day and effects of restraint stress were determined on 24 hours food intake. Plus maze activity was monitored on the 6th day after which animals were killed to collect whole brains. Administration of neem leaves extract did not alter open field activity. Restraint stress induced decrease of food intake and plus maze activity was not observed in neem extract treated rats. 2 hours restraint stress did not produce any effect on brain tryptophan levels but increased 5-hydroxyl, indoles acetic acid (5-HIAA) concentration in saline but not in neem injected rats. Administration of neem leaves extract increased brain tryptophan and decreased brain 5-HT concentration. The present study shows that neem extract could attenuate anxiogenic and appetite suppressant effect of stress by decreasing brain 5- HT and 5HIAA concentration.