A standardized fraction of Melia volkensii fruit kernel extract was tested against Anopheles arabiensis mosquito larvae. The LC50 in 48 hr was 5.4 micrograms/ml. At low concentrations this fraction had growth inhibiting activity producing prolonged larval instars, and lethal effects during ecdysis. Further fractionation of the standardised fraction yielded seven bands on preparative Thin Layer Chromatography. The two most lipophilic bands had acute toxic effects on the larvae, the next two bands had growth inhibiting effects, while the three trailing bands had no effect at all. The acute toxicity and growth inhibiting effects were destroyed by heat during the drying of the fruits.