We reported an 80-year-old Chinese woman on chronic stable dose of warfarin who experienced two episodes of an elevated international normalized ratio (INR) after drinking herbal tea containing Lycium barbarum L. Our case illustrated the potential herbal-drug interaction between warfarin and L. barbarum L. in keeping with a previous case report. Enquiry about herbal intake may be a crucial part in the management of anticoagulation in this locality.