This paper details the very first extensive study of the shift toward antibiotic resistance in french hospital. Escherichia coli (1205 strains) where collected between 1962 and 1968 and submitted to a MIC susceptibility test for 6 antibiotics widely used during these years. Freeze-dried strains (25 strains) originaly cultivated in 1950 were used as control. The statistical analysis of the data has clearly demonstrated the increase of the resistance level for Ampicillin, cephalosporin, Colistin and Neomycin and the apparition of resistant sub-populations. A similar approach was used for Staphylococcus aureus with the analysis of 9724 diffusion susceptibility tests obtained between 1965 and 1969. For most of the 19 antibiotics tested, an increase toward resistance was statistically demonstrated. This study demonstrate on a large scale that the evolution of the resistance to antibiotics was an on-going phenomenon since the beginning of the antibiotic therapy. [The original paper has no summary, this summary has been written in 2019 by one of the authors (JP Flandrois)]