The larvicidal effect of series of 3-[(2-chloroquinolin-3-yl)methyl] quinazolin-4(3H)-ones, 5a-e, against Chironomus tentans Fabricius has been investigated. The results showed that tested compounds demonstrated strong larvicidal activity, and caused high percentage of mortality after 24 h at the doses of 40-100 μg/ml, especially in the case of 3-[(2-chloro-8- methyquinolin-3-yl)methyl]quinazolin-4(3H)-one, 5b, that act as a promising larvicidal agent.