Twelve male subjects were given placebo or 160 mg propranolol, in divided doses, during a 24-hr period before drinking a beverage containing 0 or 50 ml ethanol/70 kg body weight. Tests designed to measure mental and motor performance were administered 75 min after the last dose of propranolol. The tests performed included the wobble board (WB), pursuit meter (PM), delayed auditory feedback (DAF), pegboard (PB), tapping, time estimation (TE), and a modified Cornell medical index (CMI). A mean blood ethanol concentration of 48.0 +/- 9.1 mg/dl and a mean plasma propranolol level of 33.1 +/- 13.1 ng/ml were achieved. Ethanol alone significantly impaired performance in 12 out of 20 tests (p less than 0.05). Propranolol significantly (p less than 0.05) antagonized the decrement in psychomotor performance induced by ethanol on the PM. In all other tests, there was no significant interaction between ethanol and propranolol. Propranolol alone had no significant effect on the psychomotor tests. When the drugs were combined, the subjective symptoms, as measured by the CMI, showed a trend toward being additive. This study suggests that no adverse interaction occurs between therapeutic doses of propranolol and minimum impairment doses of ethanol.