Abstract The aims of the present study were (a) to determine the presence of Ixodes ricinus in three different areas of the National Park of Abruzzo; (b) to search for the presence of Borrelia burgdorferi in the collected sample of Ixodes; (c) to determine the seroprevalence of B. burgdorferi antibodies and E. chaffeensis antibodies in inhabitants of the park and in park workers. The presence of B. burgdorferi in Ixodes was checked by PCR. For the detection of antibodies to B. burgdorferi all sera were assayed by ELISA as screening test and by Western blot as confirmatory test. For the detection of antibodies to E. chaffeensis all sera were assayed by IFA. Antibodies to B. burgdorferi were present in 9.1% of the park workers, 4.5% were confirmed positive by the IgG Western blot test. None of the inhabitants of the park was positive. Antibodies against E. chaffeensis were found in 4.5% of the park workers and 8% of the inhabitants of the park. The results obtained in the collecting of the ticks seem to show that the presence of I. ricinus in the park territory is rather discontinuous and small in number, therefore it is not epidemiologically significant for the transmission of B. burgdorferi sensu lato. Serological study for Ehrlichia revealed a high frequency of E. chaffeensis antibodies in the park inhabitants and a lower prevalence in the park workers.