Epinephrine (0.6 respectively 1.2 mg/kg] and DBcAMP* [200 mg!kg] injected intravenously in chickens enhanced appreciably the erythrocyte carbonic anhydrase within 20 minutes. In vitro, using suspensions of erythrocytes, epinephrine had the same effect. In hemolysates with added A TP and theophylline, epinephrine (0.1 mM] as weil as fluoride (10 mM] enhance carbonic anhydrase activity up to 50% within 15 minutes. The same effect is obtained by addition of cydic AMP [90-600 J.LM].