SDS-PAGE, immunoblotting and serological methods such as microimmunofluorescence (MIF) test and ELISA were used to compare protein and lipopolysaccharide (LPS) profiles and antigenicity of 12 Coxiella burnetii strains isolated mostly from ticks in Europe and Mongolia with three reference C. burnetii strains originating from USA, namely Nine Mile from tick, Priscilla from goat placenta and S from human heart valve. Among strains from Europe and Mongolia, no significant differences in protein and LPS profiles were observed, irrespective of their origin, i.e. the country and source of isolation. The LPS profiles of these strains appeared to be more related to those of Nine Mile strain associated with acute Q fever, than to those of strains S and Priscilla associated with chronic Q fever. In immunoblots all strains isolated from Slovakia and Poland reacted more expressively with rabbit serum against Nine Mile than with serum against Priscilla strain. In the MIF test and ELISA there were no substantial differences in antibody-binding capacity between the reference and newly isolated C. burnetii strains, except for strain Priscilla reacting with homologous serum in lower antigenic concentration than other strains under study. However, in the MIF test much higher antigenic concentrations of each C. burnetii strain was required to detect antibodies in the Priscilla serum than in the Nine Mile, Luga and S sera.