OBJECTIVE To investigate the association between CYP3 A4 and CYP3 A5 gene polymorphism and the efficacy and adverse reactions of paclitaxel in patients with tumor.METHODS Sixty-seven patients who re-ceived paclitaxel chemotherapy from February 2016 to February 2020 were selected as experimental subjects,the CYP3 A4∗1G and CYP3 A5∗3 genotypes were detected,and the patients were divided into wild type group and mu-tant group.After 2 cycles,the efficacy and adverse drug reactions were evaluated,and the correlation between the effi-cacy and adverse drug reactions of patients and the polymorphism of CYP3 A4∗1G and CYP3A5∗3 gene was ana-lyzed.RESULTS Among 67 tumor patients,there was no significant difference between wild type group and mutant group of CYP3 A4∗1G and CYP3 A5∗3 in efficacy and adverse reactions(P>0.05).CONCLUSION CYP3 A4∗1G and CYP3 A5∗3 gene polymorphisms were irrelative with the efficacy and adverse reactions of paclitaxel.