Harmaline doses of 25 or 50mg/kg were administered i.p. to albino rats, the animals being killed 3 h later. Falck-Hillarp’s fluorescence microscopic method and Björklund’s method for the evaluation of 5-hydroxytryptamine and nor adrenaline were applied. On the base of the spectro photofluorometric measurements one can suggest that harmaline entered actively but in a rather limited extent both noradrenergic and 5-hydroxytryptaminergic nerve cell bodies. It also entered the nerve tissue diffusely without any preference. The working hypothesis that harmaline could function as a false transmitter could not, however, be certi