We assessed plasma concentrations of fibronectin (FN) and thrombospondin (TSP) during acute attacks and attack-free periods of patients with familial Mediterranean fever (FMF). Seven female and three male FMF patients (mean age 34+/-7 years) were enrolled in the study. Plasma samples were obtained during acute FMF attacks and after 3 months of freedom from attacks. Erythrocyte sedimentation rate, C-reactive protein, and white blood cell count were evaluated concurrently. Plasma levels of FN and TSP were assayed by enzyme-linked immunosorbent assay (ELISA). Both FN and TSP concentrations were found to increase during acute attacks. Levels of adhesive molecules decreased during attack-free periods (P < 0.05). Significant correlations were found between FN and TSP levels and the concentrations of acute-phase response indicators (P< 0.05). This study disclosed for the first time significantly higher increments in the plasma levels of FN and TSP during acute FMF attacks than in attack-free periods. Therefore, the two matrix glycoproteins may play precipitating and/or regulatory roles in the inflammatory processes of these attacks.