Background/ Aims: Evaluation of the risk factors, and phenotype- genotype correlation of familial Mediterranean fever ( FMF) gene ( MEFV) and serum amyloid A1 ( SAA1) gene polymorphisms in renal amyloidosis. Methods: We investigated MEFV and SAA1 genotypes (alpha,beta, and gamma isoforms) in 50 FMF patients and 50 healthy children. Tel- Hashomer criteria were used for the diagnosis and severity scoring of FMF. Results: The most common MEFV mutation and SAA1 genotype were M694V/ M694V ( n = 26/ 50) and SAA1 alpha / alpha ( n = 26/ 50), respectively. Positive family history for amyloidosis was significantly higher ( p < 0.001) with more severe clinical course ( p = 0.006) in the amyloidosis group than the non- amyloid group. In M694V/ M694V mutation, erysipelas-like skin erythema ( p = 0.029), arthritis ( p = 0.004), arthralgia ( p < 0.001) were significantly more frequent with higher severity scores ( p = 0.008) than the patients with other mutations. Comparison of the SAA1 alpha / alpha genotype with other genotypes revealed more frequent arthritis ( p = 0.003) in the SAA1 alpha / alpha genotype. In amyloidosis group patients having both M694V/ M694V and SAA1 alpha/alpha genotypes were the largest subgroup ( n = 14, p < 0.001). Logistic regression analysis for amyloidosis corrected risk revealed a 1.2 times increase in M694V/ M694V, a 2.4 times increase in SAA1 alpha / alpha genotypes and a 2.5 times increase when both are together. Conclusion: Positive family history for amyloidosis and presence of SAA1 alpha / alpha genotype in M694V/ M694V mutation may predispose to amyloidosis by increasing the clinical severity. Therefore, in such children early colchicine treatment might be recommended even if they are asymptomatic. Copyright (C) 2005 S. Karger AG, Basel.