Abstract: Forelimb buds from 12th day mouse embryos were dissected and cultured in 0.5,1.0,2.0 and.410mg K₂Cr₂O₇/LMEM+10%rat serum cultur ed for 6 days. The mouse forelimb development of the 0.5 and 1.0 mg. L- 1 groups were not significantly differ ent fr om the contr ols wher eas the higher concentr at ions resulted in a concentration related deterior at ion in limb developmen and differ entiation. The results indicated that potassium dichromate can inhibit mouse limb bud development and differ entiation in vitro. It is a potential developmental to xic substance in mice.