Abstract Electrophoretic analysis of esterases was carried out on a total of 37 strains of Sitophilus oryzae, S. zeamais and S. granarius. Polymorphism rate was higher in S. zeamais than in the two other species. Esterase characters allow the three species to be distinguished and confirm that S. oryzae and S. zeamais are closer to each other than to S. granarius. They also allow differentiation between populations of the same species, but do not indicate the geographical origin of all populations. A high mixture of populations due to the transport of cereals all over the world could explain such a result.