The purpose of this study was to investigate the cytotoxicity of orthodontic bands in vitro and in vivo.4 types of orthodontic bands were applied to cultured fibroblast and the supermatants were injected into dorsal subcutaneous tissue of mice. In vitro, the cytotoxixity was evaluated by an MTT assay after 2 and 6days.In vivo, the histopathologic observation was performed 2 days after injection. The results were : 1. The cell viability was significantly decreased in the group added phosphoric acid in comparison to control group, but there was not any significance among the experimental group after 2 days. 2. Cell viability decreased in the high Ni containing group after 6 days. 3. The histopathological finding was that the Cr-containing group showed severe infiltration of inflammatory cells and muscular destruction.