Two vascular tumors in two Argentine horned frogs (Ceratophrys ornata) are described. Case 1 involved a 7-yr-1-month-old Argentine horned frog that had a splenic mass with a sanguineous coelomic effusion. Histologically, the splenic parenchyma was effaced by a poorly demarcated, invasive mass consisting of spindle cells with marked nuclear atypia forming irregular blood vessel channels containing blood. Case 2 involved a pedunculated facial mass located at the upper right lip of an over-8-month-old Argentine horned frog. Histologically, the well-demarcated, poorly cellular mass consisted of sparse proliferation of spindle cells forming irregular slits with prominent edema. Immunohistochemically, the neoplastic cells of both cases were positive for anti-CD31 antibody. The diagnoses were hemangiosarcoma in Case 1 and lymphangioma in Case 2. To the best of the authors' knowledge, this is the first description of neoplastic diseases in captive Argentine horned frogs.