Studies of insect vectors may be facilitated by using laboratory colonies. However, it has been suggested that the colony insects are not representative of natural populations, sometimes yealding to erroneous interpretations of the intraspecific genetic variation between the individuals. In the present study the variability of the mitochondrial gene cytochrome b was evaluated among a closed laboratory colony of Anopheles albimanus that was founded 20 years ago and the field population from which it was derived. The analyses revealed the presence of five and three nucleotide haplotypes in the wild and colony populations, respectively. Wild individuals presented greater variability than those of the colony based on the number of polymorphic sites, haplotype diversity, nucleotide diversity and mean values of nucleotide differences. The mean and net numbers of nucleotide substitutions per site between populations and the significant F ST value calculated (0,37179, P = 0.05) indicate that there is a considerable degree of genetic differentiation between them. The phylogenetic tree showed that the colony haplotypes appear to be derived from the wild population. These results suggest a great genetic variability in wild specimens compared with the laboratory ones as a consequence of a long time of colonization.