Cervical cancer is one of the most common cancer in women. The high mortality rate indicates that chemotherapy has not overcome cancer disease. Strategies and development of cervical cancer treatment should be pursued. Avocado leaf (Persea americana Mill) is one of natural product that had antioxidant activity by scavenging radicals and cytotoxic activity. The aim of the study was to identify the cytotoxic activity on HeLa cervix cancer cells and to identify the chemical subtance groups of avocado leaves ethanol extract as chemopreventive agent. Active contents of avocado leaves was extracted by maceration with 96% ethanol. Chromatographic test were done to identify the chemical substances of avocado extract. Cytotoxic activity of avocado leaves ethanol extract was measured using MTT assay. The result of the phytochemical screening with thin layer chromatography test showed that the extract of avocado leaf contained flavonoids, alcaloids, and saponin. Avocado leaves ethanol extract inhibited HeLa cell growth with the IC50 of 360 µg/mL. Morphology of Hela cell showed that extract inhibited cell growth in dose dependent.