The occurrence of parasitic infections in Nile tilapia (Oreochromis niloticus (Linnaeus, 1758)) cultured in Sinaloa, Mexico were investigated. Fish samples were obtained from different fish farms over the last 11 yr. In total, 433 fish were examined and 13 parasite species (8 protozoans and 5 monogeneans) were found. Trichodina spp., Cichlidogyrus spp., and Gyrodactylus spp. were the most-common parasites and occurred in most years, reaching prevalences of 81, 60, and 48%, respectively. Trichodina spp. and Cichlidogyrus spp. were the only species to be found in 5 fish farms in the same year, which occurred in 2008. These results suggest that parasite infections in farmed tilapia have likely become permanently established in Sinaloa, probably because of the poor water quality and incorrect management practices. We argue that better educational programs are needed to correctly comply with biosecurity measures to prevent and control fish diseases.