Spontaneous retroperitoneal hemorrhage (SRH) is a potentially lethal complication of anticoagulation therapy. The signs and symptoms vary from clinical silence to abdominal pain or hemorrhagic shock. The diagnosis of SRH may be difficult, especially in its early clinical course, due to its varied symptoms. Physicians need to have a high degree of suspicion for its early diagnosis. Delayed diagnosis of SRH can lead to serious complications or death. Bleeding complications in anticoagulated patients are well known; however, reports about SRH with fatal outcomes are sporadic. Here, we describe a case of massive SRH in a patient receiving enoxaparin. In our case, the patient died due to delayed diagnosis and treatment. We, therefore, emphasize that physicians should always consider SRH in any patient receiving anticoagulants who presents with abdominal pain.