The effects of 7 days of pretreatment with atenolol, 150 mg day‐1, or nadolol, 80 mg day‐1, on the pharmacokinetics and metabolism of theophylline were determined in six male smokers. Theophylline clearance, volume of distribution, half‐life and the urinary excretion of theophylline and its metabolites were unchanged during either treatment compared with control. 1990 The British Pharmacological Society