One hundreds and forty-nine patients (221 ears) suffering from tinnitus were treated by an intravenous administration of Xylocaine. Xylocaine, 1mg per kg, was administered once a week. The immediate effect of Xylocaine on tinnitus was evaluated subjectively for all the patients. The long term effect in 57 patients who received Xylocaine administration more than 12 times was also analyzed. The results can be summarized as follows. 1. Short and long term relief of tinnitus was obtained in 165 of 221 ears (74.7%) and in 35 of 57 cases (61.4%), respectively. 2. This therapy was more effective in old patients and in the patients with low pitch tinnitus, or with positive residual inhibition. 3. The numbers of the effective cases increased after the 8th time administration of Xylocaine. Thus we recommend the Xylocaine administration at least 8 times. 4. The results of the loudness balance test were not correlated with the change of the subjective improvements. 5. The suppressive effect of tinnitus by injecting saline solution intravenously was recognized in 24 of 73 cases. At present, repeated administration of Xylocaine would be one of the most significant therapies of tinnitus.