The steam distilled oil of the overground parts of Artemisia monosperma was analysed by chromatographic and spectral techniques. The oil was found rich in dibenzofuran (36%), l-phenylbicyclo [3.3. I] non-2-en-9-01 benzoate (25%) and octahydrophenanthrene (12%). It contains also diphenylamine (2%) which is a strong hypoglytemic. The biological study revealed that the oil possesses a larvicidal effect which is mainly due to the presence of dibenzofuran.