In order to study expression of human leukocyte antigen-DR (HLA-DR) and chondroitin sulfate proteoglycan (CS-PG) in human coronary artery , 13 coronary arieries including normal group (n=6) and lesion group (n=7),which were fixed with formalin, embedded in paraffin and slided successively (4μm ), were stained with HLA-DR and CS-PG microwave immunohistochemistry. Then the slides were quantitated with image analyzer. Results indicated that the numerical density of HLA-DR positive cells and the area density of CS-PG in the intima of lesion group were evidently higher than that of normal group, and were significantly correlative with that of normal group. One of lesion group was stained with proliferative cell nuclear antigen (PCNA) and CD68. Similar localization of CD68 and HLA-DR was found in intima. Menatime, positive cells of HLA-DR mostly were positive ones of PCNA. These results indicated that expression HLADR in earlier As lesion was closely related with formation of foam cells, proliferation of SMC and increase of CS-PG.