Six different extracts from Eucalyptus citriodora leaves were investigated for their anticancer effect. Extracts were prepared using a range of polar and non-polar solvents to leach out maximum active components. Phytochemical analysis of the extracts revealed the presence of anthraquinones, cardiac glycosides, flavonoids, saponins and tannins. Cytotoxic activity of different extracts was tested in vitro against seven human cancer cell lines from seven different tissues, such as SW-620 (colon), HOP-62 (lung), PC-3 (prostate), OVCAR-5 (ovary), HeLa (cervix), IMR-32 (neuroblastoma) and HEP-2 (liver). The ethyl acetate, chloroform and 50% methanolic extract displayed highest anti-proliferative effect in a dose-dependent manner. In vivo anti-tumor activity was evaluated against murine tumor (solid) model of Ehrlich ascites carcinoma and Sarcoma 180. The results showed that ethyl acetate and aqueous extracts suppressed the growth of Ehrlich ascites carcinoma (29.79% and 18.48%, respectively), but showed little growth inhibition in case of Sarcoma 180 (13. 86% and 8.57%, respectively). The activity might be due to the flavonoids, tannins and saponins that are present in all the extracts of the plant. Further investigation is required for the isolation of active principle(s) from the ethyl acetate extract, which has shown significant in vitro and in vivo anticancer potential.