Abstract: We studied under microcosm conditions the degradation of endosulfan and its effect on soil microbial respiration, soil microbial population and pH evolution in three major soil types of Burkina Faso. Results indicated that the recommended treatment dose of endosulfan (3 μg g-1) did not affect soil pH. But when the dose was 6 μg g-1, a stimulation of the respiratory activity of the soils during the first five days and a disturbance of the pH were observed. There were no significant impact of endosulfan at 3 and 6 μg g-1 of soil in the total bacterial number. After 5 days of incubation the degradation rate of endosulfan with initial concentration of 3 μg g-1 were 50, 56.5 and 83.5% in the soil from Boni, Farakoba and Kaibo, respectively. But when the initial concentration of endosulfan was 6 μg g-1, the figures were 94.6, 79.6 and 20.4%, respectively. Endosulfan degradation in these three soils led to a production of endosulfan-sulphate.