Remeflin is known as an analeptic which stimulates the bulbar respiratory center, thereby causing an increase in pulmonary ventilation. The author observed the effect of Remeflin upon respiration i.e. tidal volume, minute volume and respiratory rate, and circulation, i.e. blood pressure and pulse rate, in postanesthetic patients. Ventilatory and circulatory changes were measured at 2 minutes. intervals up to 30 minutes. after intravenous injection of the drug (0. 25 mg/kg) to 40 patients in the recovery room. The results were as follows: 1) Remeflin significantly increased tidal volume and minute volume. 2) Remeflin did not significantly alter respiratory rate, blood pressure and pulse rste. 3) Improvement in the respiratory function by Remeflin was due to an increase in the depth of respiration. 4) Side effects by Remeflin were absent except for navsea or vomiting in a few cases.