Abstract Introduction: Breast cancer was the top cause of cancer deaths in 2020 with a death toll of 685 000 worldwide. Breast cancer treatments are based on drug specificity for unique receptors on the surface of some breast cancer types, there is a search for alternative treatments that are inclusive of different breast cancer types. Evidence suggests that antioxidants offer a protective effect against certain cancers. Studies on Ipomoea cairica have reported potential anticancer activity, hence this study aimed to assess the antioxidant and antiproliferative potentials of the extracts of Ipomoea cairica on three breast cancer cell lines. Materials and Methods- The study protocol was approved by the University of the Free State Health Sciences Research Ethics Committee (HSREC), with approval number: UFS-HSD2022/0353/2607-0001. Ipomoea cairica stem and leaves were harvested and identified by Prof. H. Baijnath, Department of Conservation Science, School of Life Sciences, University of KwaZulu-Natal, Durban, South Africa, with specimen number 29 30 DD housed at the Ward Herbarium. The dried plant was extracted sequentially using organic solvents ranging from non-polar to polar and water. The extracts were filtered and concentrated using a rotary evaporator and then evaporated to dryness/lyophilized. Cells were cultured according to standard established procedure. The extracts were subjected to phytochemical analyses. FRAP, DPPH, and ABTS assays were done to examine antioxidant activity and MTT assays were used to evaluate the antiproliferative/cytotoxicity of the extracts against normal (Vero) and breast cancer cell lines (MCF-7, MDA-MB-231, and 4T1). Results and Discussion- Extracts of Ipomoea cairica possess alkaloids, saponins, phenols, flavonoids, phytosterols, tannins, triterpenoids, and anthraquinones. The results from the DPPH and ABTS assays revealed that the methanol and ethyl acetate fractions had significantly the highest antioxidant potentials while the methanol stem extract exhibited the most significant antioxidant activity in the FRAP assay. The DCM stem extract showed the highest antiproliferative activity against all tested cell lines. Conclusion- Extracts of I. cairica possess significant antioxidant properties and antiproliferative activities against a wide array of breast cancer types including the most challenging triple-negative breast cancer. The plant would make for a strong herbal candidate for adjuvant therapy with breast cancer medication. Citation Format: Ayodeji Mathias Adegoke, Doreen Kulabako Kyagaba, Nomonde Hadebe, Nandi Mabaso, Relebohile Patricia Lefojane, Himansu Baijnath, Oyeronke Adunni Odunola, Mamello Patience Sekhoacha. Antioxidant and antiproliferative activities of Ipomoea cairica extracts on three breast cancer cell lines. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3829.