The expression of Fc gamma RI, Fc gamma RII, and Fc gamma RIII (the IgG receptors CD64, CD32, CD16) as well as CR3 (the C3bi receptor, CD11b) on monocytes in the blood of patients with systemic lupus erythematosus (SLE) was investigated. The relationship between the receptor expression and the serum immune complex (IC) concentration was analysed. The decrease in mean fluorescence intensity (FI) of the Fc gamma RII of patients' monocytes stained by specific monoclonal antibodies (MoAb IV3) was very close to statistical significance (P = 0.052). The expression (FI) of CR3 (using MoAb OKM1) on monocytes of patients was also decreased, but not significantly. The detected decrease of Fc gamma RII and CR3 was inversely correlated with the high circulating immune complex level in patients' sera. At the same time, Fc gamma RI expression on SLE monocytes (using MoAb 32) was significantly elevated and this change was in parallel with the serum IC concentration.