Lettuce, a vegetable is often eaten raw, is one of the most cultivated leafy vegetables in South Benin. Its consumption is growing and associated with the problems of microbiological contamination. The specific objective of this study is to determine the concentration of bleach and the time required to eliminate on lettuces almost all the total mesophilic flora, flora of Escherichia coli and Staphylococcus with coagulase-positive. After a preliminary survey on the products used by the populations of South Benin for the disinfection of lettuce, the bleach was selected and then tested in the laboratory. The experiment consisted in determining, for each bacterial species, the number of residual bacteria in samples of lettuce that had remained in the bleach at different concentrations and during different contact times namely 5 min, 10 min and 15 min. Bleach at 12° chl (3.6% active chlorine), purchased commercially, was diluted to 1/100th (0.12° chl), 1/200th (0.06° chl) and 1/500th (0.024° chl) with tap water respectively in three sterilized stainless-steel containers. The results of our study suggest that bleach at 0.06° chl for 15 min would be effective in substantially removing both the flora of Escherichia coli and coagulase-positive Staphylococcus which are germs harmful to human health.