The authors present the results of a 6-year study of tsutsugamushi fever at the Kuril islands. The area of the disease proved to include Southern Kuril islands - Shikotan and Kunashir. The principal natural carriers of tsutsugamushi among the mouse-like rodents and trombiculidae larvae were revealed; highly virulent strains were found to prevail among the tsutsugamushi rickettsia strains. Tsutsugamushi fever in the population is characterized by a benign course, pyrexia, primary affects and lymphadenitis.