Occurrence of borreliosis in human population is associated with possibility of contact with the biological vector of this disease - a common European tick, Ixodes ricinus. Therefore, the highest number of cases of Lyme disease has been recorded among forestry workers and inhabitants of wooded areas. Diagnostics of borreliosis is based on immunoserologic tests - ELISA or indirect immunofluorescence method, Western blot technique, or on increasingly popular DNA examination using the polymerase chain reaction (PCR). In the present study, where 61% of the forestry workers were seropositive, we also tried to find a correlation between the results of serological tests and PCR tests with the clinical state of the patients. Despite finding IgM antibodies in 10 persons tested, which would indicate their recent infection, no DNA of B. burgdorferi s.l. was detected in their blood. Also, no DNA of this bacteria was present in 8 persons with IgM and IgG antibodies. No genetic material of the bacteria was found in persons with IgG antibodies, indicating the possibility of chronic infection. The clinical data suggested past symptomatic infection (ECM), or even more often, asymptomatic infection with B. burgdorferi.