A study was carried out to investigate effects of cadmium stress on growth of rice seedlings, mitosis and chromosomal aberration of root tip cells. Results show that root elongation and the mitotic index of the root tip cells were significantly decreased with the increasing Cd concentration and treatment duration. Cd increased the proportion of metaphase cells, while decreasing those of prophase, anaphase and telaphase cells. Cd induced chromosomal aberrations of different types of root tip cells at their metaphase and anaphase, with frequency rising with Cd concentration and treatment duration. C-mitosis and chromosomal bridge were the main types of chromosomal aberration in root tip cells exposed to 1~10 μmol L^-1 Cd for 24 h, accounting for 32.64%～78.29%, while the percentage of chromosomal adhesion, chromosomal breakage and micronuclei for 76.44%～93.96% in root tip cells exposed to 25~200 μmol L^-1 Cd for 24~72 h. All these results suggest that Cd obviously retards mitosis and induces chromosomal aberration in root tip cells of rice seedlings.