In France Q fever is a notifiable disease, but information could only be obtained from fragmental inquiries. Routine serologic examination of 75 901 sera during the years 1982-85 showed 430 Q fever positive sera (mean rate 0.57%). Our laboratory could confirm 135 cases of clinical Q fever. In the region of Dijon, 4.4% of the country population was seropositive, but among breeders 25% were positive. 36 persons (8%) among 245 employees of the departmental veterinary services were seropositive, some with very high titers, but without obvious clinical symptoms. It seems that infection by Coxiella burnetii is still largely underestimated.