By researches carried out in male adult rats (Wistar), the influence of the intraperitoneally injected bufotenin (5 mg/kg b.w. active substance in saline solution) was followed on: I--feeding behavior; II--the serotonin concentration in hypothalamus, rhinencephalon, mesencephalon and sensorimotor cerebral cortex. The obtained results show that bufotenin influences the feeding behavior by reducing the motor functions. Its action depends on the physiological state of the animal: by increasing the alimentary motivation the rats can escape the bufotenin influence, showing a normal behavior; bufotenin does not influence the sensorials, the natural dispositions and the excitability level of the feeding and satiety hypothalamic centers. Bufotenin increases serotonin concentration only in the mesencephalic region, but not in the other studied regions. The results are interpreted as a primary bufotenin action on the serotoninic vasoconstrictive receptors at the mesencephalic level, thus disturbing the serotonin-releasing processes and possibly other chemical neurotransmitters.