Introduction With the work of Young et al. in 1951,1 and McGeer et al.,2 and others, interest has been reawakened in aromatic metabolism in psychiatric patients. Recent work with serotonin3 and the hallucinogenic effect of compounds containing the indole nucleus4 has focused interest more specifically on the possible role of endogenous indole aromatic compounds in mental disease. The current literature is replete with conflicting reports concerning abnormalities in indole excretion.5 Kety6 has pointed out many of the potential sources of error in these studies including diet, medication, and technical errors in the analytic procedure. We are currently engaged in studies with the purpose of evaluating these "extraneous" sources of abnormalities in studies of indole excretion in man. Among other factors, we are studying the effect of nonspecific stress on indole compound excretion. Studies by Knox7 and other have shown that corticoids produce