This work aimed to study whether urinary tumor necrosis factor (TNF)-like weak inducer of apoptosis (uTWEAK) level has a predictive and/or diagnostic value in lupus nephritis (LN). 73 patients with systemic lupus erythematosus (SLE) fulfilling the 1997 revised criteria for the classification of SLE and 23 age/ sex- matched healthy control included in this study were subjected to full history taking, clinical examination, routine laboratory investigations as well as measurement of uTWEAK level. uTWEAK levels were significantly higher in SLE patients with active LN compared to those without or with inactive renal disease and normal healthy subjects