The mutagenic potential of rHu-EPO was evaluated using the short-term genotoxicity tests including Ames, chromosome aberration and micronuclei tests. In Salmonella typhimurium assay, rHu-EPO did not show any mutagenic response in the absence or presence of S9 mix with TA98, TA100, TA1535, and TA1537. In chromosome aberration test, rHu-EPO did not show any significant effect on Chinese Hamster Ovary(CHO) cells compared with control. In micronucleus test using male ICR mice, a dose-dependence increase in the frequency of micronucleuted polychromatic erythrocytes(MNPCEs) was observed in bone marrow cells treated with rHu-EPO. However, it was related to the secondary effect of rHu-EPO and the number of MNPCEs was equal to spontaneous frequency. These results indicate that rHu-EPO does not show any positive response in short-term genotoxicity assays.