Purpose: This study was to determine the protective effects of Dioscoreae Rhizoma on the Mouse Embrio Fibroblast (MEF) cells exposed to the ultraviolet rays(UVA). Methods: The samples were assigned randomly to five groups; control group without any treatments, UVA group exposed only to UVA, DR group exposed only to the Dioscoreae Rhizoma, UVA-DR group exposed to UVA before being treated with the Dioscoreae Rhizoma, and DR-UVA group treated with the Dioscoreae Rhizoma before being exposed to UVA. The survival rate of cells, metabolic rate of cells, transformation of nucleus within cells, alteration of cell cycle, effects on the apoptosis, the change of the amount of protein related to cell cycle were measured in order to determine the cell protective effects of the Dioscoreae Rhizoma on each group. Results: 1. DR-UVA group has more cell protective effects compared to the UVA group in all experiments, indicating that the Dioscoreae Rhizoma protects skin from UVA physically and chemically. 2. UVA-DR group shows more efficiency compared to UVA group in rapid recovery of damaged cell and leading highly damaged cells to apoptosis, preventing the expression of abnormal cells. Conclusions: Dioscoreae Rhizoma has effects of protecting MEF cells from UVA, of recovering cells damaged by UVA, and of prohibiting the expression of abnormal cells.