An enquiry carried out on 20 French rheumatology units led us to find, out of a total of 1,202 cases of non-tuberculous osteo-arthritis of the adult, 137 gram negative bacillary infections. These were 64 cases of spondylodiscitis and 73 cases of septic arthritis, due mainly to Escherichia Coli, Pseudomonas and other enterobacteria. The frequency of gram-negative bacilli was 11.4% i.e. 9.2% in the case of arthritis and 15.6% in the case of spondylodiscitis. It is higher than in the middle of this century but does not seem to be progressing now. However, the seventy of this type of infection, which may cause important functional sequelae and numerous deaths (8 patients) justifies the routine search for these bacilli in appropriate culture media, in order to test their sensitivity to antibiotics.