Abstract This work aimed to evaluate the cytotoxic potential against cancer cells of Passiflora genus plant species cultivated in Brazil and identify the mechanism of cytotoxicity induced by the most promising extract. Leaf extracts from 14 Passiflora (P.) species were obtained ASE and in vitro cytotoxicity evaluated against cancer cell lines using MTT assay at a single concentration of 50 μg/mL. Additionally, the IC 50 of the P. alata (ELPA) leaf extracts was determined against both tumor (HCT-116, SF-295, OVACAR-8, and HL-60), and non-tumor cells (PBMC). The ELPA flavonoids were identified by HPLC-DAD and UHPLC-MS/MS. The morphological analyses used light and fluorescence microscopy, and cell cycle and DNA fragmentation analyses used flow cytometry to determine the mechanism of cell death induced by ELPA in HL-60. Among the Passiflora leaf extracts evaluated; ELPA stood out with high cytotoxic activity, followed by P. capsularis and P. quadrangulares with varying high and low cytotoxic activity. ELPA presented high cytotoxic potency in HL-60 (IC 50 19.37 μg/mL), yet without cytotoxic activity against PBMC, suggesting selectivity for tumor cells. The cytotoxic activity of ELPA may well be linked to the presence of ten identified flavonoids. Cells treated with ELPA presented the hallmarks typical of apoptosis and necrosis, with cell cycle arrest in the G2/M phase. Conclusion: From among the studied species, ELPA presented greater cytotoxic activity, possibly a consequence of synergistic flavonoid action which induces cell death by apoptosis and necrosis.