We determined the relative utility of inflammatory markers in evaluating disease activity in adolescent patients with inflammatory bowel disease (IBD). Sixty-one adolescent patients and 50 age and sex matched volunteers who served as controls were evaluated prospectively. The erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), white blood cell count (WBCC), and the leukocyte adhesiveness/aggregation (LAA) test were determined in each patient. There were 28 subjects in remission and 33 in relapse. Their percentage of aggregated white blood cells in the peripheral blood was 7 +/- 5 and 16 +/- 8, respectively, when compared with the control group (5 +/- 3) (p < 0.0001). Moreover, the LAA test was the only one which could effectively classify patients with IBD into their correct diagnostic categories of remission, mild-moderate, or moderate-severe disease activity. The LAA test is superior to other acute phase reactants used in daily practice to detect the presence of inflammation as well as for the assessment of its severity in adolescent patients with IBD. In addition, our findings may have biological relevance to the disease process and its potential manipulation by anti-adhesive agents.