A simple, selective and sensitive method has been developed to determine debrisoquine and 4-hydroxydebrisoquine in human urine. Separation of the analytes was obtained using a mobile phase of 0.1 M sodium dihydrogen phosphate-acetonitrile (87:13, v/v) and a muBondapak C18 column. The column effluent was monitored with fluorescence detection at 210 nm (ex) and 290 nm (em). Rapid sample preparation was achieved by solid-phase extraction columns (Bond Elut CBA, 3 ml capacity) which provided excellent recovery values for both compounds. The cost per sample using this approach could be minimized by column regeneration and re-use. The within-day and the day-to-day reproducibilities were less than 7% for both components. The method was shown to be suitable for the study of the debrisoquine-sparteine type genetic polymorphism in man.