Since April 1972, we have used the method of continuous intravenous infusion of thiopentoned tubocurarine mixture in 74 cases which were not required fully muscular relaxation during operation such as orthopedic operation, laminectomy, and mastoidectomy etc. The results were as follows. 1. The average needs of thiopentone and d-tubocurarine were 430mg/hr and 6.5mg/hr. 2. There were no specific changes on blood pressure, pulse rate and respiration. 3. The average recovery time was 20 minutes. 4. This method was very simple, economic and no risk of explosion.