Data on the leucine aminopeptidase system during ontogenetic growth in Anopheles nuñez-tovari revealed six areas of activity, of which LAP1, LAP2, LAP4 and LAP5 were present in the larval, pupal and adult stages and LAP3 and LAP6 were characteristics of the last two stages. Pifferences in intensity were detected according to the stage considered. LAW and LAP5 show a weak intensity in all the stages and LAP2 and LAP4 show intense activity in the larval stages, decreasing in the pupa and adult. Considering the functions of the enzymes, admitted that LAP3 in the pupae stage may be related to hystolysis of the larval tissues. Of the six loci detected, allelic variation was observed only for the LAP5 locus, with of codomi-nant action. The frequencies of genotypes among the progeny of females inseminated naturally deviate significantly from the Hardy-Weinberg equilibrium.