A method for the determination of propranolol and six of its metabolites, as well as their glucuronide and/or aryl sulfate conjugates in human urine is described. Propranolol and its basic and neutral metabolites are extracted into ether at pH 9.8, evaporated to dryness, reconstituted, separated on a reversed-phase, high-pressure liquid chromatographic system and quantitated using fluorescence detection. The aqueous urine aliquot is then made acidic and the acid metabolites extracted and measured using similar methods. The presence of 2% sodium metabisulfite in all urines collected is essential to ensure the stability of 4-hydroxy-propranolol during collection and storage. Preliminary data is presented from 24-h urine samples collected from three patients chronically receiving propranolol.