The most common life-threatening hematologic emergencies include hemorrhage and severe anemia. Successful treatment of these conditions depends on the emergency veterinarian having a thorough understanding of the possible etiologies of these conditions, and a systematic approach to diagnosis and therapy. Use of blood component therapy can be a life-saving technique in these patients. The goal of this article is to familiarize the emergency veterinarian with a systematic approach to the diagnosis and treatment of hematologic emergencies.