The cytotoxicity against brine shrimp of the essential oil obtained from the leaves of Annona senegalensis Pers. (Annonaceae) was studied. The confirmation of this toxicity has been done by using selected tumor cell lines (A549, HT29, MCF 7, RPMI, and U251). The results showed that the total oil and its fractions have showed mild to moderate cytotoxicity in brine shrimp lethality bioassay with LC50 = 27.3 μg/ml, and against some human tumor cell lines. The total oil and its fractions were analyzed by gas chromatography/mass spectroscopy (GC/MS). Seventy three compounds were identified.