Background: Lupus nephritis (LN) is clinically evident in 50-60% of patients with SLE, and it is histologically evident in most SLE patients, even those without clinical manifestations of renal disease. Lupus nephritis is diagnosed by clinical and laboratory manifestations that meet ACR criteria (persistent proteinuria > 0.5 g per day or greater than 3+ by dipstick, and/or cellular casts including red cell, hemoglobin, granular, tubular or mixed). a review of the ACR criteria has recommended that a spot urine creatinine/protein ratio >0.5 can be substituted for the 24 hours protein measurement, and “active urinary sediment” (>5 RBC/hpf, >5 WBC/hpf in the absence of infection, or cellular casts limited to RBC or WBC casts) can be substituted for cellular casts an additional, perhaps optimal, criterion is a renal biopsy demonstrating immune complex-mediated glomerulonephritis compatible with lupus nephritis. Matrix metalloproteinases (MMPs) are a group of Zn2+-dependent proteins that are found in the extracellular milieu (ECM) of various tissues. Based on sequence homology and substrate specificities, the MMPs can be classified into several subgroups including collagenases, gelatinases, stromelysins, matrilysins and the membrane-type metalloproteinases. There is considerable overlap in substrate specificities, and the MMPs appear to be involved in degradation of abundant ECM components, including laminins, collagens and fibronectin, but also in the release and turnover of cytokines and cell surface receptors of adjacent cells. MMP-7 is commonly expressed in epithelial cells, including the liver, the ductal epithelium of exocrine glands in the skin, salivary glands, and pancreas, and the glandular epithelium of the intestine and reproductive organ and breast. Under normal physiologic conditions, adult kidney exhibits little MMP-7 expression. Early identification and diagnosis are important for slowing the progression of kidney affection in SLE and preventing its complications. Serum creatinine and blood urea nitrogen (BUN), two widely used markers for the diagnosis of kidney deterioration, increase only in the advanced stage of nephropathy. So, kidney affection are usually diagnosed at a later stage, and the implementation of therapeutic interventions is usually delayed. Therefore, there is an urgent need to develop biomarkers for early detection and prognostic assessment of renal flares in LN.