Human infection by Babesia microti has been recognized as an emerging zoonosis with important public health implications worldwide. In Europe the reported cases of human babesiosis have been attributed mostly to B. divergens infection, with only sporadic cases of the disease caused by B. microti or B. venatorum. This study, based on molecular methods (PCR, R-T PCR, DNA sequencing and phylogenetic analysis), reveals for the first time in Poland, asymptomatic infection with . microti in immunocompetent healthy individuals working in forest ecosystems. Of the 58 professional foresters examined, two (3.4%) were identified as B. microti-positive by specific PCR. The results of this study also provide strong evidence that in eastern Poland, where tick-borne diseases (TBDs) are endemic, there is a potential risk of acquiring human babesiosis due to zoonotic B. microti parasites commonly found in rodents and I. ricinus ticks. The potential public health importance of this finding is discussed.