Tigecycline, a glycylcycline-derived antibacterial that has been approved for the treatment of various infections, is widely used for multi-drug resistant bacteria. Coagulopathy is an uncommon side effect during tigecycline treatment and is easily overlooked when it occurs. We reported the effect of tigecycline (50 mg every twelve hours) treatment in an 87-year-old man, with Gram negative bacillary pneumonia and respiratory failure. After 7 days of tigecycline treatment, a significant drop of hemoglobin and patchy ecchymosis over both thighs were suddenly observed despite stable clinical condition. There was no abnormality in his platelet count and coagulation profile except for low fibrinogen level. Ecchymosis and anemia subsided gradually after blood component therapy. Although his clinical condition improved, hypofibrinogenemia persisted and recovered after 5 days of tigecycline discontinuation, suggesting probable tigecycline associated hypofibrinogenemia.