Abstract - Green areas at four localities in the Belgrade region (Ada Ciganlija, Košutnjak, Miljakovac Forest, and Mt. Avala) were investigated in 2004. The aim of the research was to clarify the faunistic composition, relative abundance, and population dynamics of ticks, as well as the seasonal distribution of Borrelia burgdorferi sensu lato (sl) in Ixodes ricinus. Two species of ticks were detected: Ixodes ricinus and Dermacentor reticulates. Relative abundance analysis revealed that the species Ixodes ricinus was predominant (97.41 %). Out of 942 Ixodes ricinus ticks, 188 (19.96 %) were infected with Borrelia burgdorferi sl. The infection rate of adults by localities ranged from 19.16% to 30.99% (Mt. Avala and Ada Ciganlija, respectively).