Nitrogen-13-labelled beta-phenethylamine[( 13N]PEA) was synthesized by Hofmann rearrangement of [13N]phenylpropionamide prepared from phenylpropionyl chloride and aqueous [13N]ammonia solution. The reaction proceeded rapidly with a fairly good yield. [13N]PEA was isolated using preparative thin-layer chromatography, and organ distribution in mice was studied preliminarily. After i.v. administration of [13N]PEA, high accumulation and long-term retention of the radioactivity were observed in the brain and the heart.