Mosquitoes occupy a major health problem, as a potential vector for the transmission of many pathogens, the most important of which in Morocco are Plasmodium parasites and West Nile fever virus. Acquiring knowledge about the biotypology of these mosquitoes is an essential step in any control strategy. Thus, the objective of this study is to draw up an inventory of the culicidian fauna in the Fez region (North-central part of Morocco) and to determine the physicochemical parameters influencing the production of mosquito larvae of aquatic habitats in this area. Mosquito larvae of the extant biotopes were sampled every two months between November 2015 and December 2016, by means of the "dipping" method. The physicochemical parameters of the various larval biotopes were collected six times during the year of follow-up. Mosquito species were identified using morphological criteria. The results were analyzed using ecological indices and the generalized linear model (Poisson model) on R software. The identification of the 1,122 mosquito larvae collected from the various studied breeding areas revealed the presence of 11 species belonging to two subfamilies (Culicinae and Anophelinae) and five genera (Anopheles, Culex, Culiseta, Aedes, and Uranotaenia). Anopheles were observed in small numbers in permanent, stagnant, and shallow habitats. The larvae of s. l. (major vector of malaria in Morocco) were collected. larvae, especially . (the main vector of WNV in Morocco), were collected in the majority of the larval habitats and on the different types of environments. Two other species of Culex, which plays a significant role in the transmission of WNV, were also collected, particularly, and . The results found, this first study of its kind at the regional level, also made it possible to update the list of Culicidae species reported in the Fez region. Four new species have been recorded: , , , and . The results of this study will contribute to the provision of information for entomological surveillance and to better plan and guide vector control activities at local and national levels.