Photodynamic therapy (PDT) is a new treatment choice for ovarian carcinoma. Hematoporphyrin monomethyl ether (HMME) is a novel photosensitive reagent developed in China. This study was to investigate the photodynamic effect of HMME-based PDT on human epithelial ovarian cancer cell line SKOV3.After an incubation with 30 microg/ml HMME for different time, the fluorescent image and intracellular location of HMME in SKOV3 cells were observed under a fluorescent microscope and laser scanning confocal microscope (LSCM). After being treated with different doses (5-50 microg/ml) of HMME and irradiated with different optical doses (1.5-12 J/cm(2)) of laser, the survival rate of SKOV3 cells was measured by MTT assay. Mechanisms of cell death during PDT was determined by Annexin V/PI double staining technique and analyzed by flow cytometry.Red fluorescence appeared shortly after administration of HMME and localized in cytoplasm; intracellular fluorescence intensity reached the peak after 3 h. High concentrations of HMME alone had cytotoxicity to SKOV3 cells, while laser irradiation alone had no effect on cell survival. Survival rate of SKOV3 cells was gradually decreased along with the increase of HMME concentration and laser dose, but such a trend diminished when HMME concentration reached 40 microg/ml. After treatment of HMME, the dead cells were predominantly necrosis cells.HMME has a photodynamic effect on SKOV3 cells.