Former attempts to restore weight loss in psychiatric patients have included hyperalimentation (Weir Mitchell, 8) and sub-coma insulin therapy (Debenham et al., 2; Sargant and Craske, 5; Sullivan, 7). The aim of the present trial was to compare weight gains in a group of patients given repeated small doses of insulin with two other groups to whom oral hypoglycaemic agents were administered, and with a control group. The drugs used were tolbutamide and chlorpropamide, both of which are sulphonylureas used in the management of diabetes mellitus, and known to induce hypoglycaemia in non-diabetic subjects (Hoenig and Gittleson, 4; Cardonnet et al., 1; Garcia Reyes et al., 3). Pharmacologically there are no qualitative differences in their mode of action. Stowers et al., (6) found the half-life of tolbutamide to be 3·5 hours and that of chlorpropamide 34·5 hours. The prolonged action of chlorpropamide permits once daily dosage, but tolbutamide, being a shorter acting drug, was given in divided doses to maintain depression of blood sugar over the 24 hours.