Titanium dioxide (TiO2) is widely used nanoparticle all over the world. In this study, we have investigated the histopathological effect on zebrafish ovaries after exposure to TiO2 nanoparticles. Adult zebrafish individuals were exposed to 1, 2 and 4 mg/L TiO2 for 5 days, and then their ovaries were evaluated using light and transmission electron microscopy. Numerous degenerated follicles with cytoplasmic vacuolization, mitotic catastrophe in mitochondria , chromatin condensation, mitochondrial vesiculation and dispersion at ooplasm were observed. In mitochondria, mitotic catastrophe , vesiculation, swelling and loss of organization of cristae were detected.Here we showed that TiO2 exposure trigger paraptotic type cell death in zebrafish ovary.