A suburban focus of Lyme borreliosis situated 11 km from the southern border of the city of Lublin (eastern Poland) was characterized. The focus covers an area of circa 100 km², surrounding 3 localities inhabited by circa 7,500 people engaged mostly in farming. It was demonstrated that on the area of focus the infection rate of Ixodes ricinus ticks with Borrelia burgdorferi, frequency of serological response of inhabitants to the antigen of Borrelia burgdorferi, and incidence of Lyme borreliosis were significantly (p<0.001) greater compared to the whole territory of Lublin province, and were respectively 13.1% vs. 4.7%, 33.0% vs. 13.7%, and 0.002% vs. 0.00075% .