Bufotenine (5-hydroxy-N,N-dimethyltryptamine) has been reported to be behaviorally inactive or only very weakly active in man and animals; this may be a consequence of its low partition coefficient and resultant inability to penetrate the blood--brain barrier. The acetyl, propionyl, butyryl, isobutyryl, and pivalyl esters of bufotenine were prepared for future pharmacological evaluation. Unexpectedly, it was found that these esters all possess a relatively high affinity for the serotonin receptors of the isolated rat stomach fundus preparation. A semiquantitative chromatographic measurement of ester hydrolysis suggests that extensive hydrolysis of the esters to bufotenine does not occur under the conditions of the affinity assay.