Two of the major, naturally occurring, tryptamine hallucinogens are N,N-dimethyltryptamine (Dl'1aTnd 5- methoxy-N,N-dimethyltryptamine (5-MeO-DMT). Although they are active in man only parenterally, it has been found that the N-isopropyl homologs of these two bases are both orally active, and have human potency similar to their methyl counterparts. N,N-Diisopropyltrypt- amine (DIPT, I) effects a passive and neutral psycho- tomimetic state, but one that embodies an unusual degree of auditory distortion, both in the pitch and the timbre of perceived sounds. N,N-Diisopropyl-5-methoxytrypt- amine (5-MeO-DIPT), on the other hand, produces a talk- ative and disinhibited state with easy emotional ex- pression.