With the rapid spread of pyrethroid resistance in the main malaria vectors from Benin there is a need to monitor organophosphate and/or carbamate resistance in mosquitoes, vectors of many human diseases. The current study aimed to evaluate temephos tolerance in larvae of Anopheles gambiae sensu lato and of Culex quinquefasciatus from Dogbo district in south-western Benin in West Africa. Larvae of Anopheles gambiae s.l and of Culex quinquefasciatus mosquitoes were collected from breeding sites using the dipping method in may 2021 during the great rainy season in Dogbo district. A batch of 25 larvae of third or fourth instar were exposed to temephos according to WHO larval bioassays protocol. Larval bioassays were performed on these collected mosquito larvae using temephos as larvicide. The results showed that both larvae of Anopheles gambiae sensu lato and of Culex quinquefasciatus from Dogbo district were resistant to temephos with high tolerance in Culex quinquefasciatus. Temephos tolerance is already present in larvae of mosquitoes from Dogbo district in south-western Benin and need to be monitored carefully. Insecticide resistance monitoring is essential to help national program to implement more effective and sustainable vector-borne disease control strategies in the country.