A 35 KDa protein referred to as F3 was purified from the seeds of Borreria hispida by precipitation with 80% ammonium sulphate and gel filtration on Sephadex G-100 column. RP-HPLC analysis of protein fraction (F3) on an analytical C-18 column produced a single peak, detected at 220 nm. F3 showed an apparent molecular weight of 35 KDa by SDS PAGE and MALDI-TOF-MS analyses. Peptide mass fingerprinting analysis of F3 showed the closest homology with the sequence of 1-aminocyclopropane-1-carboxylate deaminase of Pyrococcus horikoshii. The protein (F3) exhibited significant cytotoxic activity against lung (A549) and cervical (HeLa) cancer cells in a dose-dependent manner at concentrations ranging from 10 µg to 1000 µg/mL, as revealed by the MTT assay. Cell cycle analysis revealed the increased growth of sub-G0 population in both cell lines exposed to a concentration of 1000 µg/mL of protein fraction F3 as examined from flow cytometry. This is the first report of a protein from the seeds of Borreria hispida with antiproliferative and apoptotic activity in lung (A549) and cervical (HeLa) cancer cells.