Angiogenesis plays an important role in many types of cancer. Interleukin-8 (IL-8) is known to be a pro-inflammatory and pro-angiogenic cytokine, and IL-8 has been reported to be associated with tumor progression, prognosis and survival in several types of cancers. However, the role of IL-8 in non-Hodgkin's lymphoma (NHL) has not been fully determined. Here, we evaluated the usefulness of measuring serum and urine IL-8 levels in patients with NHL. We developed reference intervals for serum and urine IL-8 level in 131 control individuals. We measured serum IL-8 and urine IL-8 levels in patients with NHL, and we compared the concentrations with those of control individuals. The reference intervals for serum IL-8 and urine IL-8 corrected by creatinine (Cr) were 15.9-430.3 pg/mL and 0.0-28.4 pg/mg Cr, respectively. The concentrations of urine IL-8/Cr were significantly higher in patients than in controls (48.9+/-194.4 vs. 5.2+/-13.8 pg/mg Cr, P<0.001). However, there were no significant differences in serum IL-8 concentrations between NHL patients and controls (159.2+/-40.4 vs. 99.6+/-107.1 pg/mL; P=0.099). Receiver operating characteristic (ROC) analysis gave 0.83 and 0.43 ROC area values for urine IL-8/Cr and serum IL-8, respectively. There was no correlation between the serum and urine concentrations of IL-8 and clinical variables, the only exception being the international prognostic index (IPI), which showed a marginal correlation with urine IL-8/Cr levels (P=0.07). This study indicated that urine IL-8/Cr levels might be useful as a diagnostic marker of NHL.