Abstract: OBJECTIVE To improve the clinical recognition of daptomycin induced artificial prolongation of prothrombin time/international normalized ratios(PT/INR). METHODS Clinical data of a case of daptomycin induced abnormal prolongation of PT/INR were retrospectively analyzed, and reviewed the literature. RESULTS Abnormal prolongation of PT/INR in this patient was considered to cause by daptomycin interacting with some test reagents of PT. Therefore, the patient didn't receive vitamin K therapy, and warfarin was added in time to reduce the risk of thromboembolic events. CONCLUSION With the emergence of drug-resistant bacteria, the clinical application of daptomycin is gradually increasing, abnormal prolongation of PT/INR in patients who treated with daptomycin should be paid more attention, especially for the warfarin users, coagulation function should be tested by other methods to decrease mistakes in clinical treatment due to defects in test methods.