An unsexed, 16-year-old blue-and-gold macaw (Ara ararauna) was presented for evaluation of rapidly growing subcutaneous masses at the left tibiotarso-tarsometatarsal joint. Results of incisional biopsy were diagnostic for an intermediate-grade soft-tissue sarcoma. A distal-femoral amputation was performed and the leg was submitted for histopathology. Histopathologic examination confirmed the biopsy diagnosis and revealed neoplastic spread into the bone marrow cavity of the tibiotarsus. Excisional margins were complete. The macaw recovered and did well until it died suddenly 32 months after surgery. At necropsy, death was attributed to acute hepatic hemorrhage. No recurrence or metastasis of the sarcoma was identified.