We have, related preliminary results on protein polymorphism in two natural populations of Anopheles darlingi from the Amazon region (Ariquemes, state of Rondonia, and the Highway PA-422, in the state of Para). Fοr the esterases there were observed variations in the locus Est-2in the Ariquemes population, while while locus was onomorphic in the Highway PA-422 population. In the later population we found individuals showing the genotype. Est2*F/Est2*F. The allele frequency Est2*Fhas been estimated at 0,80 in the population of, Ariquemes, this value being much higher than the one related to our previous study on the Highway BR-174 (Manaus/Boa Vista) which was 0,48. The results concerning leucine-aminopeptidases (LAP) suggest that this enzyme is controlled by three apparently monomorphic loci in the both populations.