Abstract 1. 1. Intravenous injection of chlorpromazine (CPZ) into sheep increased plasma glucose concentration from 3.4 to 5.6 mM and long chain fatty acid concentration from 0.29 to 0.40 mM within 10 min. Glucose returned to steady state within 210 min and fatty acid within 120 min. 2. 2. Plasma glucose kinetics were evaluated with a primed infusion of [6- 3H] d-glucose. 3. 3. The CPZ-induced hyperglycemia was caused by a large increase in glucose influx (from 8.6 to 70 μmol/min per kg) which was of short duration (20 min). 4. 4. The hyperglycemia was resolved by a moderate increase in glucose outflux (from 8.6 to 24 μmol/min per kg) which was of long duration (210 min).