There is no routine test to evaluate the activity of Behçet's disease (BD). Ferritin as a serum predictor of iron storage is an important acute phase reactant. In this study, we assessed serum ferritin levels in patients with active BD and compared them with those of patients with inactive BD. We aimed to show the relationship between ferritin and BD. The patients with BD were subdivided into two groups according to disease activity: active (24 patients; 18 men and 6 women, average age 36.5 +/- 4.9 [28-45] years), and inactive (20 patients; 16 men and 4 women, average age 37.2 +/- 5.2 [30-49] years). Twenty healthy volunteers (15 men and 5 women; average age 38.2 +/- 4.6 [30-47] years) served as controls. Patients with active BD had significantly higher serum ferritin levels (p=0.0001) than the inactive and control groups. Ferritin levels in patients with inactive BD did not differ significantly from healthy control subjects (p=0.687). We concluded that in patients with active BD, serum ferritin levels are increased and do not reflect serum iron levels.