Rapid increases in cancer and human death cases, as well as the fatal side effects of chemotherapy, have forced the seek new safer anti-cancer drugs. Therefore, the current study was conducted to study the effect of Graviola leaf extract on the proliferation of human breast cancer (MCF-7) cell lines. MCF-7 cells were cultured and a Neutral red uptake assay was done to estimate the effect of Graviola extract on MCF-7 cells'''' proliferation. Treatment with different concentrations of Graviola leaf extract inhibited the proliferation of MCF-7 cells in a concentration-dependent manner. Conclusion: Graviola leaf extract has a promising inhibitory effect against the proliferation of MCF-7 cells.