Biliary atresia (BA) is a neonatal obliterative cholangiopathy of unknown etiology. Despite the Kasai procedure, hepatic fibrosis and portal hypertension (PH) still occur. Interleukin-8 (IL-8) is an important mediator of inflammation and immune response in human disease. The objective of this study was to investigate the potential role of IL-8 in the pathogenesis of the progressive, sclerosing, inflammatory process and fibrosis in BA. A total of 60 pediatric patients with BA and 15 healthy children were evaluated. The mean ages of BA patients and controls were 6.3 +/- 0.6 and 6.7 +/- 1.1 years, respectively. The patients were classified into two groups according to their clinical outcomes: patients with jaundice (total bilirubin +/- 25.5 micromol/l) and patients without jaundice (total bilirubin < 25.5 micromol/l). The IL-8 levels in serum samples were determined by commercially available enzyme-linked immunosorbent assay. Serum IL-8 levels were higher in the BA patients than in healthy children (236.2 +/- 60.1 vs. 34.5 +/- 12.1 pg/ml, P < 0.001). Patients with jaundice had lower levels of albumin but had greater levels of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and gamma glutamyl transpeptidase compared with patients without jaundice. Serum IL-8 levels in the jaundice group were significantly higher than in those without jaundice (516.5 +/- 130.0 vs. 49.3 +/- 10.4 pg/ml, P < 0.0005). Furthermore, patients with PH had higher IL-8 levels than those without PH (378.1 +/- 102.2 vs. 106.6 +/- 48.4 pg/ml, P < 0.005). In the jaundice-free group, IL-8 levels were elevated in patients with PH compared with those without PH (79.0 +/- 17.4 vs. 19.7 +/- 5.8 pg/ml, P < 0.005). The present study demonstrated elevation of serum IL-8 levels in children with BA. Serum IL-8 levels were also higher in patients with jaundice compared with patients without jaundice. These findings suggest that IL-8 may play a significant role in the pathogenesis of BA.