The two-carbon homologs of two potent psychotomimetic agents are described. Unlike the parent isopropylamine compounds (4-methyl-2,5-dimethoxyamphetamine, DOM, STP; and 4-bromo-2,5-dimethoxyamphetamine, PBR, 4-BR) these phenethylamines lead to an intoxication state which is, in normal subjects, of short duration and of greatly increased sensory enhancement, but which does not superimpose hallucinogenesis. These two phenethylamines, 4-methyl-2,5-dimethoxyphenethylamine (II) and 4-bromo-2,5-dimethoxyphenethylamine (III), are active in man at oral levels of 0.1 to 0.2 mg/Kg, approximately one tenth the potency of their three-carbon counterparts.