In order to assess the level of occupational exposure to the main pathogens transmitted by the Ixodes ricinus tick, a seroprevalence study was performed on serum samples collected in 2003 from 2,975 forestry workers of North-Eastern France. The global seroprevalence estimated for the seven pathogens studied was 14.1% (419/2,975) for B. burgdorferi sl, 5.7% (164/2,908) for F. tularensis, 2.3% (68/2,941) for TBEV, 1.7% (50/2,908) for A. phagocytophilum, and 1.7% (48/2,908) for B. henselae. The seroprevalence of B. divergens and B. microti studied in a subgroup of subjects seropositive for at least one of these latter pathogens was 0.1% (1/810) and 2.5% (20/810) respectively. B. burgdorferi sl seroprevalence was significantly higher in Alsace and Lorraine and F. tularensis seroprevalence was significantly higher in Champagne-Ardenne and Franche-Comté. The results of this survey also suggest low rates of transmission of B. henselae and F. tularensis by ticks and a different West/East distribution of Babesia species in France. The frequency and potential severity of these diseases justify continued promotion of methods of prevention of I. ricinus bites.