Objective: To determine the frequency and the degree of the nailfold capillary abnormalities in patients with familial Mediterranean fever (FMF). Methods: We studied 67 (M/F: 28/39) patients with FMF. Thirty-seven healthy subjects (16/21), 19 patients (0/19) with systemic lupus erythematosus (SLE), and 8 patients (0/8) with scleroderma (PSS) were also studied. All participants were questioned for the presence of Raynaud's phenomenon (RP). Capillary loops of eight fingers were evaluated and scored with respect to avascular areas, tortuosity, enlargement and extravasations by the conventional capillary microscopy. Both FMF patients and healthy controls were examined in a blind manner. Results: FMF patients differed from healthy controls by the presence of increased tortuosity and enlargement of capillary loops, but not by microhemorrhages. Being female and the presence of RP were the factors that correlated with the capillaroscopic findings. Conclusion: Capillary abnormalities are seen in patients with FMF. © Copyright Clinical and Experimental Rheumatology 2001.