1. Attemption to verify the overwintering method of Xanthomonas oryzae, the causal organism of rice leaf-blight, using specific X. oryzae phage was made. 2. It was found from the results that the X. oryzae could overwinter in diseased leaves of rice plants. On the unhulled grain, the presence of the bacteria was determined at a initial 30 days only. With the soil which was collected from the diseased paddy, negative results were obtained. 3. Generally speaking, soil contains many kinds of microorganisms which change the pH value of media by producing acid or alkali at the culture period of this technique. As it is clear in the last report that the phage is inactivated rapidly in the media in which pH values were under 4 or above 12. Still more it must be considered the relation between the phage and soil colloidal particles under various conditions. So it is difficult to conclude that there are not present the objective bacteria in the sample which shows negative results.