The P-gp/MDR1 multidrug transporter mediates detoxification of numerous drugs, including colchicine, and CYP3A4 is key to the biotransformation of colchicine. We investigated the effects of CYP3A4 and P-gp/MDR1 polymorphisms on bioavailability of colchicine in patients with Familial Mediterranean fever (FMF). Forty-eight Turkish patients with FMF treated with colchicine were genotyped for 3435C>T, (-)1A>G, 61A>G, 1199G>A, 1236C>T, 2677G>A, 2677G>T polymorphisms in the P-gp/MDR1 gene and 3435C>T, 1B(-392A>G), 2(15713T>C), 3(23171T>C), 12(21896C>T), 17(15615T>C) polymorphisms in the CYP3A4 gene. Doses of colchicine administered to patients did not differ with respect to P-gp/MDR1 or CYP3A4 gene polymorphism. We also determined the genotype distributions of CYP3A4 and P-gp/MDR1 genes among FMF patients. There was no significant gender difference in the P-gp/MDR1 polymorphism, whereas there were significant gender differences in the frequencies of 15713T>C and 15615T>C polymorphisms in the CYP3A4 gene. No significant relationship was found between colchicine doses that would introduce optimal clinical response and affect the therapeutic dose and CYP3A4 and P-gp/MDR1 gene polymorphisms in these FMF patients.