7,N,N-Trimethyltryptamine (TMT) was synthesized and evaluated as an inhibitor of synaptosomal biogenic amine uptake in rat forebrain homogenates. In addition to inhibiting 3H-serotonin uptake (IC50 = 0.4 micrometer), TMT appears to be quite selective and is much less potent in blocking either 3H-norepinephrine or 3H-dopamine uptake (IC50 = 180 micrometer and 61 micrometer, respectively).