This paper reports the toxic properties of nano-TiO2 on 2 different early life stages of Xenopus laevis. Synthesis of nano-TiO2 particles was carried out by the hydrothermal method. Characterization of nanoparticles was performed using spectral techniques including X-ray diffraction, scanning electron microscopy, and a particle-size analyzer. Embryos at the 8th stage and tadpoles at the 46th stage were exposed to 7 concentrations of nano-TiO2 in the range of 5 to 320 ppm. After 96 h of exposure, the mortality percentage of each exposure concentration was calculated and the activity of enzyme biomarkers acetylcholinesterase, carboxylesterase, glutathione S-transferase, glutathione reductase, lactate dehydrogenase, and aspartate aminotransferase were determined in living embryos and tadpoles. None of the tested concentrations of TiO2 caused statistically significant mortality or malformation (only for the embryo test) as compared to the control groups. Furthermore, we did not observe any significant changes in enzyme activities in tadpole samples from the 46th stage, although some minor changes not related to the concentrations were observed in embryos.