Securidaca longepedunculata is a savannah shrub found growing in SouthWest Nigeria and some other areas in Africa. It has been reported to be used in the treatment of over a hundred ailments. Its root bark is included in several anti-cancer decoctions in Nigeria. Despite its reported use as an anti-cancer plant, there is a dearth of information on the anti-cancer potential of Securidaca longepedunculata in Nigeria. The aim of this research is to determine the cytotoxic and antimitotic activity of aqueous root bark extract of Securidaca longepedunculata. Securidaca longepedunculata aqueous root-bark extract was prepared and used for the study. Cytotoxic activity of S. longepedunculata extract was determined by the brine shrimp toxicity assay and Allium cepa assay was used to assess the anti-mitotic activity. Brine shrimp toxicity assay showed an LC50 of 25.1 µg/mL and the Allium cepa assay revealed that 100 mg/mL extract caused a reduction in mitotic index (MI) which was comparable to that of the standard drug, methotrexate. Securidaca longepedunculata has potential as a cytotoxic agent.