Etomidate (0.3 mg/kg) and thiopental (4 mg/kg) were administered IV for induction of general anesthesia, comparing heart rate, blood pressure, respiration, and side effects. No significant difference between the drugs was found in the circulatory parameters, but respiration was more depressed by thiopental. A high incidence of the side effects of myoclonia and pain on injection was seen with etomidate. The incidence of side effects was not affected by speed of injection or type of premedication. Mechanisms to reduce the incidence of side effects are needed for etomidate to become a useful induction agent.