Fifteen elderly patients whose hypertension was controlled by conventional propranolol 80 mg twice a day had their medication changed to one capsule of Inderal LA¹ (160 mg) daily. The blood pressure, heart rate and propranolol concentrations were measured at various time points when the patients were receiving the conventional preparation and these assessments were repeated when the long-acting preparation was administered. Although the heart rate was lower with conventional propranolol than with Inderal LA there was no significant difference in the blood pressure levels. The mean peak blood level of propranolol was, however, significantly lower with Inderal LA compared with conventional propranolol and occurred later. At 12 h the plasma propranolol levels were higher after Inderal LA than following the intake of conventional propranolol (p<0.01); there="" was="" no="" difference="" in="" the="" plasma="" levels="" at="" 24="" h.="" the="" area="" under="" the="" concentration="" time="" curve="" was="" significantly="" higher="" on="" conventional="" propranolol.="" compared="" with="" published="" data,="" the="" plasma="" levels="" were="" higher="" than="" those="" in="" younger="" patients.="">Inderal LA was well tolerated and side effects were minimal.