The frequency of anti-Borrelia burgdorferi antibodies in human sera of various groups of people from the Lublin region was studied. In the indirect immunofluorescence test (IFT) sera from 836 forestry workers and 56 farmers occupationally exposed to ticks were examined. Fifty healthy blood donors from the city of Lublin were examined as a control group. Forestry workers showed positive response in 26%, whereas farmers in 11% and the control group in 6%. In ELISA test, sera from 44 forestry workers, 217 farmers, 458 patients from the dermatologic and neurologic clinics, and 50 blood donors (controls) were examined. A positive response was found in 38.6% of forestry workers, 28.1% of farmers, 12.2% of patients of the neurologic clinic, 27.1% of patients of the dermatologic clinic and in 6% of controls. During this study, in one of an forestry workers the diagnosis of Lyme borreliosis as the occupational disease was clinically confirmed. High percent of anti-Borrelia burgdorferi antibodies found in people exposed to ticks may suggest that Borrelia burgdorferi is widespread in the forest environment of eastern Poland and that infection often has an occupational character.