Objective: To approach to relation of TCM syndrome differentiation of chronic aplastic anemia （CAA） with polymorphism of MHC-DRB1 * allelic genes. Methods: MHC-DRB1 * allelic genes in patients of CAA and healthy control group were detected and analyzed by PCR/sequence-specific primer technique. Results: MHC-DRB1 * 0301 gene frequency in the patient of kidney-Yang deficiency was significantly higher than that in the healthy control group （P<0. 01）. MHC-DRB1 * allelic genes were not related with kidney-Yin deficiency in the patient of CAA. Conclusion: MHC-DRB1 * 0301 genes are possibly susceptible genes of kidney-Yang deficiency in the patient of CAA. or susceptible genes of CAA or a part of them

indicating that patients of this type have genetic basis of immunoregulative defect; and there is a certain inner link between MHC and disease types of congenital constitution of CAA. which can reflect genetic characteristics of TCM costitution and objectiveness of CAA TCM syndrome differentiation to a certain extent.