Following intraperitoneal administration, 5-methoxy-N,N-dimethyltryptamine and N,Ndimethyltryptamine are subject to both a very rapid uptake into, and clearance from, all tissues examined. The current studies in uioo confirm previous in oino observations that the routes involved in the metabolism of these compounds include oxidative deamination, N-demethylation, O-demethylation, and N-oxidation. The analysis of metabolic profiles in various tissues led to the identification of the N-oxides as major metabolites. The successful inhibition and redirection of metabolism away from the indole acids towards the parent compounds and their structurally unique metabolites were demonstrated in animals pretreated with iproniazid.