Abstract Over 562,340 Americans are expected to die of cancer, more than 1500 people a day. Cancer is the second most common cause of death in the US, exceeded only by heart disease. In the US, cancer accounts for nearly 1 of every 4 deaths. Our study focuses primarily on three plants never before investigated for antitumor activity. They were chosen based upon native ethno medicinal usages. Indigenous primarily to the southwestern region of Nigeria; Enantia chlorantha, Nauclea latifolia, and Citrus medica have all been traditionally used and studies have proven their noteworthy antibacterial, antimicrobial, and anti parasitical activities. These important characteristics provide the rationale behind studying these plants further for potential antitumor agents. Experimental: Methanolic leaf and bark extracts in a series of concentrations were taken from the previously stated plants and exposed to two breast and two colorectal cancer cells for 24 hours. Growth analysis is determined using a cell viability indicator alamar blue and a florescent plate reader. Results: Enantia chlorantha and Citrus medica demonstrated the most potential for containing novel antitumor compounds. However, E. chlorantha proved to be exceedingly toxic to the cellular proliferation of all four tumors cell lines at all concentrations. In addition to this, Nauclea latifolia extracts illustrated the least potential for antitumor activity. In most cases this extract showed little or no effect in reducing cellular proliferation. Conclusion: We conclude that leaf extracts from E. chlorantha and C. medica should be studied further to characterize their antitumor potential, investigate their main active compounds, and to better understand their mechanisms of action. Citation Format: Chenel M. Alford, Alexandra Onyejiaka, Elbert L. Myles. Cytotoxic activity of enantia chlorantha, nauclea latifolia, and citrus medica extracts on carcinoma cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 614.