The metabolism of the new reversible A-selective monoamine oxidase inhibitor amiflamine was studied in relation to polymorphic hydroxylation of debrisoquine in 24 healthy subjects. Amiflamine is metabolized by two consecutive N-demethylations. By construction of urinary recovery ratios analogous to that of debrisoquine/4-hydroxydebrisoquine, correlations between debrisoquine metabolic ratio and amiflamine/demethylated metabolites were significant and consistent within slow and rapid hydroxylators of debrisoquine. It is concluded that debrisoquine hydroxylation and amiflamine N-demethylation might be under common genetic regulation.