The sensitivity of 1,823 bacteriological strains of differing types is shown (E. coli, Klebsiella-Enterobacter-Serratia, Proteus-Providence, Pseudomonas, Salmonella-Shigella-Citrobacter, Haemophilus, Staphylococcus and Streptococcus); all of clinical origin, isolated during March and April, 1975. The methods used were series of double dilutions in Mueller-Hinton agar and the disc-plate method (weight of 50 μg). A comparative study is made of the sensitivity between a part of the present strains (1,725) and another group of 1,664 germs, isolated and observed in January and February, 1973. Some variations are observed which, on general lines, do not seem to be significant, except for Klebsiella-Enterobacter and Serratia