Familial Mediterranean fever (FMF) is an autosomal recessive disease. Although the possibility of multiple immunologic mechanisms have been studied, the actual mechanism is still unresolved. Forty-one patients with FMF (24 males and 17 females with a mean age and disease duration of 17.8 +/- 4.1 and 4.7 +/- 2.3 years, respectively) and 14 healthy controls (10 males and 4 females with a mean age 23.2 +/- 5.1) were involved in the study. A phagotest was studied in both the patients and control groups with a FACScalibur Flow. All patients were in the acute stages of the disease and had not undergone colchicine treatment for 2 months. The percentage blood phagocytic activity of both granulocytes and monocytes were 84.23 +/- 8.76 and 67.28 +/- 10.15 in the patient group and 94.68 +/- 3.24 and 76.23 +/- 5.7 in the control group, respectively. There was no statistically significant difference in the percentage of phagocytic activity of the granulocytes and monocytes between the FMF patients and healthy controls (p > 0.05 and p > 0.05, respectively).