The effects of a new steroid anaesthetic agent (CT1341) were studied in twenty volunteers divided into three groups. In group I, serial measurements were made of heart rate, blood pressure and respiratory rate. In group II, detailed haemodynamic studies were made in patients undergoing diagnostic cardiovascular investigations. These studies included measurement of cardiac output, stroke volume and arterial blood gases. In group III, time from induction to “true recovery” was measured following a single intravenous injection of the drug. This agent produced a stable anaesthetic state in all cases. Anaesthesia was characterized by a rise in respiratory rate and pulse rate with a slight fall in systolic and diastolic blood pressure. A significant fall in Pao2 occurred in those patients breathing air. The mean recovery time in six patients was 24.3 min. CT1341 produced safe and stable anaesthesia in all twenty cases and is worthy of further clinical trial.