The authors review the research on N,N-dimethyltryptamine (DMT) as a possible ‘schizotoxin. DMT produces psychedelic effects when administered to normal subjects, the means present to synthesize it in man, it has occasionally been found in man, and tolerance to its behavioral effects is incomplete. However, DMT concentrations have not been proven to differ significantly in schizophrenics and normal controls. Also, in vivo synthesis of DMT has not been convincingly demonstrated, and the psychological changes it produces do not closely mimic the symptoms of schizophrenia. The authors conclude that more data are necessary before the validity of this theory can determined.