The ability of beta-adrenergic receptors to adapt to reductions in stimulation might be impaired in depressed or schizophrenic patients. To test this hypothesis 12 normal controls, 12 depressed patients resistant to tricyclic antidepressants, and 8 chronic schizophrenic patients were treated with propranolol 160 mg/day for 10 days. A previous study had reported that this dose regimen led to a rise in lymphocyte beta-adrenergic receptors in normal volunteers. Blood was sampled before propranolol treatment and 60 hr after the last propranolol dose. There were no significant differences between any of the groups in lymphocyte beta-adrenergic receptors after 10 days of propranolol treatment.