Babesiosis is a protozoal disease of wild and domestic animals including some rodents and humans. Disease is transmitted by Ixodid tick vectors which are widely distributed in Turkey. Babesiosis is widespread in Turkey affecting sheep, goats and particularly cattle. In this study, the epidemiology of babesiosis in cattle and humans (by possible exposure to ticks) was investigated during the period between September 1998 and March 2000 in different regions of Turkey. A total of 464 cattle were examined at different periods of time. Blood specimens were collected from the jugular vein of the animals (into EDTA tubes), and thin blood smears were also prepared for microscopic examination. In addition, 28 human blood specimens and thin blood smears were obtained from people with a history of tick bites. A two step PCR (polymerase chain reaction) test was used to detect Babesia spp. DNA in all blood specimens. During the first PCR test, primers amplifying all Babesia and Theileria DNA's were used. Positive samples were subjected to a second PCR test where species-specific primers for B. bovis, B. bigemina and B. divergens were used. Thin blood smears were examined microscopically for Babesia spp. infected erythrocytes. The results of the PCR analysis showed that infection rates with Babesia spp. were 21.12% in Ankara, 8% in Burdur, 23.80% in Kayseri and 7.21% in Samsun. Results of microscopical examination showed that 5.63%, 8% and 2.88%, of cattle in Ankara, Burdur and Samsun, respectively, were carrying Babesia spp. piroplasms. No Babesia spp. were found in human blood samples either by microscopy or PCR.