Nomifensine, a representative of a new class of chemical substances, is a compound of low toxicity and of wide therapeutical range. Nomifensine is absorbed very well, has a rapid onset of action, has no sedative effect and does not prolong alcohol-induced anaesthesia. In studies on thymoleptic activity, nomifensine showed a good and persistent activity, particularly after oral treatment. It had a better quantitative effect than the tricyclic reference compounds from which it differs by the lack of distinct anticholinergic activity. The efficacy of nomifensine does not decrease during long-term treatment. The mechanism of action of nomifensine, whose thymoleptic activity resembles that of a tricyclic antidepressant, may be explained by the influence on the catecholamine metabolism, but contrary to tricyclic compounds, nomifensine also influences the dopamine uptake. The increase in motility induced by nomifensine is based on a different mechanism as that induced by phenylalkylamines. Particularly noteworthy are the lack of a systemic effect, the remarkably slight influence on the cardiovascular system, and the slight cardio-toxicity in comparison with reference compounds. Nomifensine showed an interesting activity component in the protective influence on stress-induced ulcers. The results of kinetic studies of nomifensine in animals explain the rapid onset of action and indicate an easy use in therapy.