Mosquitoes of 19 species belonging to 9 subgenera and 6 genera, Aedes, Aedeomyia, Anopheles, Armigeres, Culex, and Mansonia, were recorded in Sundarbans mangrove forest in West Bengal, India. With 6 and 5 species, respectively, the 2 genera Culex and Anopheles were found to be more diverse while less than 3 species were recorded in the other 4 genera. Adults were mainly collected resting on walls in the guesthouse, tree holes in the forest, landing on humans in the guesthouse, and in the forest, and in light traps. Larvae were obtained from tree holes in the forest. The list of species recorded is not conclusive due to the restriction in access to most parts of the mangroves due to the presence of tigers. The occurrence of the urban species Cx. quinquefasciatus within the Sajnakhali sanctuary is indicative of the need to monitor environmental changes that result with the introduction of man-made facilities.