A study was conducted to evaluate the larvicidal activity of solvent extracts of Hydnocarpus pentandra (Family: Flacourtiacea) seed against two mosquito species, Aedes aegypti L. and Culex quinquefasciatus Say. Crude seed extracts were prepared by hexane, chloroform, ethyl acetate and methanol solvents and larvicidal activity was studied at 62.5ppm, 125ppm, 250ppm and 500ppm concentrations against the late third instar larvae of Ae. aegypti and Cx. quinquefasciatus. Results clearly showed that the chloroform extract was the most effective treatment against both species. The median lethal concentration (LC50) values of chloroform extract were calculated as 248.28ppm and 89.52ppm for Ae. aegypti and Cx. quinquefasciatus, respectively. The LC90 values were 731.62ppm and 678.48ppm for Ae. aegypti and C. quinquefasciatus, respectively.