AimTo analyse the association of CYP3A4*1G, CYP3A5*3 and MDR1 C3435T gene polymorphisms with the antihypertensive effect of amlodipine.MethodsA total of 70 patients were screened who were diagnosed as hypertension in the first year after transplantation.The patients were assigned to receive amlodipine (5 mg/d) for 4 weeks.PCR-RFLP were applied to detect CYP3A4*1G， CYP3A5*3 and MDR1 C3435T gene polymorphism, and antihypertensive effects were analyzed according to genotype.ResultsAfter 4-weeks treatment, mean reductions in systolic blood pressure(SBP) and diastolic blood pressure(DBP) were 18.8±6.9 mmHg and 12.7±5.4 mmHg, respectively (p<0.05).Patients with CYP3A5*3*3 genotype (15.0±5.0 mmHg) had higher DBP reduction than those with CYP3A5*1*3 (11.3±5.3 mmHg) and CYP3A5*1*1 genotype (10.0±4.1 mmHg) (p<0.05).No significant relationship was found between CYP3A5*3 gene polymorphism and SBP reduction (p>0.05); Patients with CYP3A4*1G*1G genotype (8.6±4.1 mmHg) had lower DBP reduction than those with CYP3A4*1G*1 genotype（13.2±5.2 mmHg） and CYP3A4*1*1 genotype(13.1±5.5 mmHg)(p<0.05).No significant relationship was found between CYP3A5*3 gene polymorphism and SBP reduction (p>0.05); And no significant relationship was found between MDR1 C3435T and BP reduction (p>0.05).A linkage disequilibrium exists between CYP3A4*1G and CYP3A5*3 allele, GGGG, AAAA and AGAG were the most common combination.Patients with GGGG genotype can reach higher DBP reduction than other ones.ConclusionCYP3A5*3 and CYP3A4*1G gene polymorphisms can affect antihypertensive effect of amlodipine in hypertensive patients after renal transplantation, DBP reduction in patients with CYP3A5*3*3 genotype is higher, and DBP reduction in patients with CYP3A4*1G*1G genotype is lower compared with other genotypes.Patients with GGGG genotype have higher DBP reduction in all the haplotypes composed by CYP3A4*1G and CYP3A5*3.MDR1 3435T gene polymorphism was not found to be related to the effect.