In the last years, new spotted fever group rickettsial isolates were made in France and all over the world, the geographical distribution of several well known rickettsiae was determined more precisely and the number of tick vectors increased. The reasons for this rapid evolution are the recent introduction of new isolation techniques, and especially of new identification methods, like the PCR followed by enzymatic restriction of the amplified DNA. The increase in the number of rickettsiae isolated from ticks able to bite humans confronts us with several new epidemiological, taxonomical, serological and clinical problems.