Bark beetles of the genus Dendroctonus are a group of insects widely distributed in North American and Eurasia. These bark beetles feed on phloem and vascular cambium from coniferous trees. They maintain symbiotic associations complex with bacterial and fungal. In this work, the microbial diversity associated to the gut of bark beetles was studied. Guts from D. pseudotsugae, D. adjuntus; D. approximatus, D. valens were collected from several geographical sites in Mexico. The gut was obtained and sectioned in foregut, midgut, and hindgut. The DNA of these three region was used to amplify the 16S and 26S ribosomal genes with the purpose to evaluate bacterial and fungal communities by PCR-DGGE procedures. In the species studied were observed different microbial composition between foregut and midgut-hindgut. A clear difference was observed among bacterial and fungal communities of Dendroctonus species. Additionally, DGGE analysis revealed common amplification bands with previously cultured yeast, but other amplification bands had not relationship with any isolated strains. Particularly The 16S and 26S bacterial libraries and RFLP analysis from gut of D. pseudotsugae revealed limited ascomycete and bacterial diversity.