Background: Extracts of Caesalpinia mimosoides Lamk has been reported to possess anticancer effects, but the active ingredients and the anti-cancer mechanisms are still unknown. Materials and Methods: The effects of a C mimosoides Lamk extract on cell proliferation and apoptosis induction in human cervical carcinoma cell lines, namely HeLa, SiHa, and C33A, as well as in normal Vero cells, were investigated. Results: Treatment with 5 active fractions (F17-F21) of C mimosoides Lamk methanol extracts inhibited cell viability in a dose- and time-dependent manner. Neutral red assays indicated that treatment with F21 significantly decreased the viability of all cervical cancer cell lines compared to F21-treated normal cells. In addition, HPLC analysis revealed that F21 contained multiple phenolic compounds, namely gallic acid, caffeine, vanillic acid, ferulic acid and resveratrol. F21 had the lowest IC50 and, therefore, a much higher cytotoxicity than F20, F17, F19, and F18 by 20-, 25-, 46- and 47- fold, respectively. Analysis of activation of the apoptosis pathway using a caspase 3/7 activity assay revealed that F21 treatment resulted in a considerable increase in caspase activation in all cancer cell lines tested. At the same concentration of F21, HeLa cells had the highest caspase activity (6.5-fold) compared to the control. Conclusion: C mimosoides Lamk may be of value as an alternative therapeutic agent, especially in combination with other compounds offering possible of synergy of action. Moreover, HPV- and non-HPV-related cervical cancer cells may differ in their responses to treatment regimens.