OBJECTIVE: This study evaluates serum or urinary tumor necrosis factor-like weak inducer of apoptosis (TWEAK) as a biomarker for lupus nephritis (LN). METHODS: We conducted a meta-analysis examining serum or urinary TWEAK levels in patients with systemic lupus erythematosus (SLE), patients with LN (active or inactive), and healthy controls. We tabulated correlation coefficients between urinary TWEAK level and total or renal SLE Disease Activity Index (tSLEDAI or rSLEDAI). RESULTS: Eight studies were included in this meta-analysis. The meta-analysis revealed that serum TWEAK levels tended to be higher in patients with SLE than in controls (standard mean difference [SMD]=0.850, 95% confidence interval [CI]=−0.067∼1.767, p=0.069). Urinary TWEAK was significantly higher in patients with active LN than in those with inactive LN (SMD=2.865, 95% CI= −0.831∼4.898, p=0.006). In addition, urinary TWEAK was positively associated with tSLEDAI and rSLEDAI (correlation coefficient= 0.436, 95% CI=0.204∼0.622, p=4.3×10⁻⁴; correlation coefficient=0.483, 95% CI=0.108∼0.738, p=0.014). Pooled sensitivity and specificity of urinary TWEAK for diagnosis of LN were 81.3% (95% CI, 73.3∼87.8) and 76.0% (95% CI, 66.3∼84.2), indicating good diagnostic accuracy. CONCLUSION: The meta-analysis demonstrated that urinary TWEAK was significantly higher in patients with active LN than in those with inactive LN, and that urinary TWEAK levels were positively correlated with renal disease activity.