We report the case of a 59-year-old Chinese man who showed an asymptomatic coagulation factor V deficiency pattern after second intravenous treatment with ceftazidime. Normal pooled plasma failed to correct the abnormalities in a mixing test, and the presence of factor V inhibitor was confirmed by the Bethesda method. The coagulopathy was not corrected by transfusion of fresh frozen plasma and prothrombin complex concentrate, but rather by treatment with prednisone and withdrawal of dubious drugs. The findings reported here should prompt clinicians to watch for drug-induced coagulation factor deficiency.