Mosquitoes transmit a wide range of vector-borne diseases to humans and animal. Due to the increase in insecticide resistance, there is a need for novel mosquito vector control programs, including biocontrol. Some water mite larvae, such as those of Arrenurus genus, act as parasites of mosquitoes. Mosquito larvae, pupae and adults were collected from three locations in Amol County, Iran by dipping and hand-catch collection methods, from May to late September 2015. Then mites were removed from mosquitoes and identified to genus level using valid identification keys. A total of 873 adults of anopheline mosquitoes belonging to three species (Anopheles maculipennis s.lat., An. pseudopictus and An. hyrcanus) were collected. We only found Arrenurus sp. mites. From 873 anopheline mosquitoes captured, 11% were parasitized by 151 mites, with a mean rate of 1.59, ranging from 1 to 14. Parasitism was higher in lowlands. Water mites, as biocontrol agents of vectors, could impact fecundity, fertility and induce other harms on host. As this study is the first research on water mite parasitism on mosquitoes in Iran, more detailed studies are needed to increase our knowledge on biology and ecology of water mites parasitizing mosquitoes in Amol and other areas in Caspian sea region in Iran.