Objective: To elucidate the relationship between PARP-1 activation and 5-aminolevulinic acid-mediated photodynamic therapy (5-ALA-PDT)-induced cell death in ovarian cancer, specifically examining the roles of PARP-1 induced-parthanatos, apoptosis and DNA repair. Design：In vitro experimental study. Sample: Human ovarian cancer cell lines (SKOV3, A2780). Methods: OVCAR3 cells were cultured under standard conditions. First, different conditions were established for the 5-ALA-PDT group in order to validate the effect of cell death. The toxicity of the PARP-1 inhibitor (DPQ) and the caspase-3 inhibitor (z-DEVD-fmk) was pre-validated. The experimental groups were then divided into the following: a control group; a 5-ALA-PDT group; a 5-ALA-PDT + DPQ group; a 5-ALA-PDT + z-DEVD-fmk group; a 5-ALA-PDT + DPQ + z-DEVD-fmk group; and an MNNG group. Outcome Measures: CCK-8 assay for cell viability; ROS assay kit for the semi-quantitative measurement of oxygen free radicals; Western blot analysis for the semi-quantitative expression of nuclear and total cellular proteins; JC-1 assay for changes in mitochondrial membrane potential; immunofluorescence technique for the localisation of intracellular proteins; and γH2AX assay kit for the detection of DNA damage. Results: Compared with the control group, 5-ALA-PDT caused early oxygen free radical overload, mitochondrial membrane potential imbalance, DNA double-strand damage, and reduced cell viability in human ovarian cancer cells SKOV3/A2780. PARP-1 expression was upregulated, and the number of PARP-1 active product [poly-(ADP-ribose), PAR]-modified proteins was increased. AIF nuclear translocation, cleaved caspase-3 expression, and increased Bax/Bcl-2 ratio. Flow cytometry revealed that 5-ALA-PDT caused cell necrosis and apoptosis. Conclusion: 5-ALA-PDT induces parthanatos and apoptosis in human ovarian cancer cells through PARP-1.