In this brief review it will be possible to mention only superficially the bioclinical, behavioral, neurochemical, neuropharmacological and neurophysiological evidence to support the view that some of the trace amines [meta- and paratyramine (m-TA, p-TA), beta-phenylethylamine (PE) and tryptamine (T)] may play a significant role in the propagation of nervous impulses and perhaps be involved in the etiology of certain mental disorders. More detailed comments will be found in some recent papers and reviews (Axelrod et al., 1976; Boulton, 1974, 1976, 1978, 1979; Boulton and Baker, 1975; Boulton and Juorio, 1979, Faurbye, 1968; Mosnaim and Wolfe, 1978, Sandler and Reynolds, 1976; Wyatt et al., 1977).