A 17-yr-old boa constrictor (Boa constrictor constrictor) presented initially with diffuse gingival swelling, loose teeth, and loss of body condition. Examination under anesthesia revealed two firm pink masses within the oral cavity. The largest mass was removed for biopsy. Histopathology and Melan-A–positive immunohistochemistry labeling confirmed a diagnosis of amelanotic melanoma. Secondary stomatitis was treated with antibiotics to improve quality of life, but the snake's condition deteriorated quickly over the next 2 mo. Euthanasia was elected and a gross postmortem examination was performed. Gross postmortem examination and histopathology results demonstrated that the neoplastic cells had spread in an unusual symmetrical pattern along all four dental arcades: the right and left sides of both the mandible and maxilla. Histopathology confirmed metastasis throughout the liver and spleen, despite the lack of gross lesions.