The sensitivity to fosfomycin of more than 8,000 strains of bacteria isolated from products received by the laboratory between 1972 and 1974 has been studied. Some were studied by the dilution technique in a solid medium and the remainder was studied by diffusion. A single 50-μg disc was used and the strains inhibited by concentrations of less than 64 μg/ml or with inhibition halos of 15 mm diameter or more were considered sensitive. It is clear from this study that there are no significant changes in the sensitivity of the bacteria studied during the above-mentioned time, with the exception of a decrease in that of indole-positive Proteus, Providentia and Klebsiella