New, so far unknown epidemically active natural foci of tick-borne rickettsiosis have been identified in Suzun District, Novosibirsk Province. The patients had a typical clinical pattern and epidemiological history of the disease. The cases were recorded in a number of communities in the northern forest-steppe zones. The results of the epidemiological survey and rickettsial studies of Ixodes ticks and blood sera of farm animals demonstrate the existence of clear-cut natural foci of tick-borne rickettsiosis, with its main vectors being ticks D. silvarum. The infestation of ticks was proved by biotests in passive hemagglutination tests, using an immunoglobulin diagnostic kit. Some measures for the monitoring of foci and disease prevention are suggested.