A new APAAP method has been used to detect HLA-DR expression and expression intensity on monocytes in peripheral blood of 46 SLE patients and 22 normal individuals. The HLA-DR positive expression rate of monocytes averaged 77.4?9.12% and the DR antigen expression intensity on monocytes averaged 3.4?1.27?10~(-2) in 25 active SLE patients. Those of the normal individuals were 52.1?6.30% and 2.1+0.6?10~(-2) respectively. It was found that the mean value of active SLE patients were significantly higher than those of 21 remission patients (53.7?14.81%, 1.3?0.47?10~(-2)) and the normal individuals(P0.05).In SLE patients, HLA-DR positive expression rate of monocytes correlates with DR antigen expression intensity on monocytes (r 0.82,P