Wolves are commonly housed in zoological institutions and captive breeding facilities that are essential for maintaining genetic diversity and for the recovery of declining populations. Neoplasia is a common cause of mortality in wolves, but hemangiosarcoma has not previously been described. This condition was diagnosed in four red wolves (Canis rufus) and two gray wolves (Canis lupus) housed at five different institutions between 2008 and 2018. Animals were 11–16 yr of age at the time of presentation. Clinical signs included loss of body condition, abdominal distension, lethargy, weakness, ataxia, and hyporexia. Three animals were mildly anemic. All animals were humanely euthanized within an average of 3 d from onset of clinical signs. Two animals had primary splenic tumors, two had pelvic tumors with one originating from the aorta, and one had a cranial mediastinal mass. Diagnosis was made on postmortem histologic examination in all cases. Four wolves had evidence of metastases with foci in the lungs, lymph nodes, mesentery, liver, subcutis/skeletal muscle, kidney, adrenal, and thyroid gland. Hemangiosarcoma should be considered in geriatric wolves presenting with nonspecific signs, particularly if abdominal distension, free peritoneal fluid, or anemia is present.