The volatile constituents which obtained from fresh fruits of Pleiogynium timorense (Dc.) Leenh (Anacardiaceae) by hydro-distillation method were investigated by Gas chromatography and gas chromatography–mass spectrometry. Twenty seven compounds were identified representing 98.6% of the total oils. D-Limonene was the major oil constituent (64.51%), followed by γ-Terpinene (5.60%), while, α-Copaene and trans-Caryophyllene showed the same percentage (4.74%). In addition, phytochemical screening, proximate analysis, total phenolic and total flavonoid contents of the fruits were determined. Furthermore, the volatile constituents showed a cytotoxic effect against breast adenocarcinoma MCF7 and laryngeal carcinoma HEp2 human tumor cell lines and a moderate cytotoxic effect on human hepatoma HepG2 cells.