A new stereospecific hplc method that is capable of simultaneously quantitating the S-(-)- and R-(+)-enantiomers of acebutolol and its major metabolite, diacetolol, in plasma and urine, is described. When applied to the assay of biological fluids collected during single and chronic oral dosing with acebutolol (Sectral), this procedure failed to reveal any important stereoselectivity in the disposition of either acebutolol or diacetolol in man. This may occur because acebutolol is metabolized by hydrolysis and N-acetylation, whereas the other beta-blockers which exhibit some degree of stereoselective disposition (e.g. metoprolol and propranolol) are primarily metabolized by oxidation.