The ecological index (EI) as defined by Schulze et al. was determined in three localities of western Slovakia (Malacky, Podunajské Biskupice, Olichov) using the following criteria: suitability of the habitats for the occurrence of Ixodes ricinus ticks and their number, accessibility of habitat for men (I. phase); furthermore the abundance and infection rate of ticks (II. phase). A scoring procedure (point values of 1-5 for each parameter) was used to evaluate the EI of three localities studied. Based on obtained values it is suggested to differentiate foci as those with a definite (Malacky), potential (Podunajské Biskupice, Olichov), minimal and unprobable risk of transmission. The EI is considered a helpful method for assessing areas of risk for the transmission of
Lyme borreliosis, indicating also the necessity of appropriate preventive measures.