Background: The aim of the study is to assess the incidence of Lyme disease, established diagnosis based on medical history and clinical symptoms, serology, duration of exposure in the workplace and occupational disease certification among forestry workers in selected districts of the Warmia and Mazury region. Material and Methods: The study consisted of annual screening of 332 employees in 6 forest districts under the supervision of the Health Center Medica in Ostróda. Serological tests were performed in all serum samples and IgG and IgM antibodies were determined by ELISA test. Positive results were confirmed by Western-blot test. Diagnosis was made based on medical history and clinical symptoms. Results were presented by the division of selected forest districts, gender, duration of exposure in the workplace and genospecies of spirochete Borrelia responsible for the disease development. Results: Lyme disease incidence was found in all selected forest districts. Positive results in Western-blot test were determined in 120 people (63.1% of all the surveyed). However, after taking a detailed medical history of the patients Lyme disease was diagnosed in 91 people which makes 27.4% of all the examined. Among patients with diagnosed disease, IgG antibodies were found in 76 people, IgM in 25 people, while both IgM and IgG in 10 people. There was also variation in the involvement of genospecies generating the disease; spirochete B. afzeli – 46% for IgG antibodies, whereas spirochete B. burgdorferi – 50% of all cases for IgM antibodies. At the same time the relationship between the extended duration of occupational exposure to tick bites and the increased incidence of Lyme disease was confirmed, indicating the group of workers employed for at least 25 years. Conclusions: Forestry districts of the Warmia and Mazury region, creates extremely dangerous occupational conditions because of exposure to tick bites. At the same time the duration of employment significantly increases the risk of Lyme. The analysis of serological tests results indicated differences in the reactivity of IgG and IgM classes and confirmed the correlation between clinical symptoms of Lyme disease and the variation of genospecies inducing the disease. Med Pr 2014;65(3):335–341