Neutrophil gelatinase-associated lipocalin (NGAL) is an acute phase reactant in certain inflammatory conditions. The aim of this study was to investigate whether plasma NGAL is a sensitive biomarker of low-grade inflammation. The severity of inflammation was determined by a scoring system using highsensitivity C-reactive protein (hsCRP) and corrected erythrocyte sedimentation rate. The sensitivity of NGAL in low-grade inflammation was 27.3%, lower than hsCRP (73.8%, P<0.001). Plasma NGAL concentration was significantly associated with hsCRP, tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6) in high-grade inflammation, but not in low-grade inflammation. In a receiver operating characteristic curve analysis, the diagnostic value of NGAL to identify an increase in IL-6 and TNF-α was similar to that of hsCRP in high-grade inflammation. However, the area under the curve of NGAL was significantly lower than that of hsCRP in low-grade inflammation (0.579 (95% CI, 0.449-0.708) versus 0.691 (95% CI, 0.557-0.826), P<0.001). Plasma NGAL may provide helpful information when monitoring patients with high-grade inflammation but does not seem to accurately reflect the severity of inflammation in low-grade inflammation.