INTRODUCTION Glomerulonephritis is a major determinant of the course and prognosis of systemic lupus erythematosus (SLE) and is evident in 40%-85% of patients. IL10, a cytokine produced by monocytes and-to a lesser extent-lymphocytes, has pleiotropic effects in immune regulation and inflammation. It enhances B cell survival, proliferation, differentiation, and antibody production; these effects play a role in autoimmune diseases. Among identified polymorphisms in the IL10 promoter, three linked single nucleotide polymorphisms (SNPs) of -1082 G/A, 819 T/C, and -592 A/C have been shown to influence the IL10 gene expression. Compared with the -592 C allele, the 592 A is associated with lower IL10 production in vitro. The objectives of this study were to investigate the -592 A/C polymorphism in patients with and without lupus nephritis and to assess its influence on IL10 secretion in vivo and its role in pathogenesis and clinicopathological characteristics of lupus nephritis. METHODS This case control study was conducted on 40 SLE patients recruited for the study from those attending the nephrology department of the Theodor Bilharz Research Institute (outpatient clinic and inpatient ward) in 2013. Patients were divided into two groups, group I (SLE patients without evidence of nephritis) and group II (SLE patients with lupus nephritis). Data were analyzed using SPSS (version 12), a t-test, Chi square, ANOVA, and the Pearson product-moment correlation coefficient. RESULTS Our study found an increase in IL10 serum in lupus nephritis patients compared to those without renal involvement (without statistical significance). No significant differences emerged in the level of IL10 serum among different pathological classes. CONCLUSION The IL10 gene (-592 A/C) polymorphism, though not associated with lupus nephritis's susceptibility in the present study, does play a role.