Background. Familial Mediterranean fever (FMF) is an autosomal recessive disease characterized by recurring attacks of fever and serositis. The definition of the mutated gene has allowed molecular diagnosis of the disease. The most important complication of FMF is the development of AA type secondary amyloidosis. In a group of patients clinically designated as phenotype 11 amyloidosis patients, renal amyloidosis develops without being preceded by typical attacks of the disease. In this study, the mutations of the MEFV gene were analysed in a group of patients clinically recognized as phenotype II.