For many years research workers have been attracted by the idea that some endogenously produced psychotogen might be implicated in the etiology of schizophrenia. Our findings suggest that the excretion of DMT is not exclusively related to schizophrenia or even to mental illness. Nevertheless, we have now demonstrated in two separate studies that much higher levels are excreted by some acutely psychotic patients. Exactly what mental or physical features of psychosis are particularly associated with increased excretion of DMT, and whether DMT excretion is a cause or consequence of these features are fascinating but unanswered questions.