The essential oil of Artemisia judaica L., grown oil Sinai Peninsula of Egypt, was extracted via hydrodistillation. Chromatographic separation on repeated silica gel columns led to isolate two compounds namely piperitone and trans-ethyl cinnamate. Insecticidal, antifeedant and antifungal properties of the isolated compounds were examined. Both compounds showed pronounced insecticidal and antifeedant activity against the third instar larvae of Spodoptera littoralis (Boisd). trans-Ethyl cinnamate (LD50 = 0.37 mu g/larva) was more toxic than piperitone (LD50 = 0.68 mu g/larva). The two isolated compounds revealed antifeedant activity in a concentration dependent manner, with complete feeding inhibition at a concentration of 1000 mu g/ml. When tested for antifungal activity against four plant pathogenic fungi, the isolated compounds exhibited a moderate to high activity. (C) 2007 Elsevier Ltd. All rights reserved.