Babesia microti, an intraerythrocytic protozoan and the etiological agent of human babesiosis, is transmitted by the bite of the tick, Ixodes ricinus. The aim of the present study was to confirm the presence of B. microti by detection of the DNA of these protozoans. The prevalence of B. microti was studied using the PCR method with primers complementary to the gene fragment encoding nuclear small-subunit ribosomal RNA (ss-rDNA). In the course of this study a total of 2095 ticks, Ixodes ricinus, were examined. The mean infection rate was 6.2%. Variable prevelance values were also obtained from six different locations and they were further modified by the seasons of the year. The results confirmed the competence of I. ricinus as a vector of B. microti and that a B. microti-specific PCR can provide a sensitive test for laboratory detection of babesiosis.