It was shown in experiments on rats that the reaction of self-stimulation (SS) decreased the enhanced level of 11-hydrohycorticosteroids (11-HCS) in the blood after electrical pain stimulation(EPS) of the feet. Diazepam (1 mg/kg) decreased the levels of 11-HCS and beta-lipoproteids and increased the level of phospholipids after self-stimulation and pain stimulation. Diazepam and preliminary electrical pain stimulation induced activation of self-stimulation. It is concluded that diazepam and the activation of the positive reinforcing system exert similar effects on 11-HCS excretion and lipid levels after pain stimulation.