Abstract: Mixed skin tumors are uncommon in dogs. This study reports the clinical findings, radiography, ultrasonography, histopathology and clinical outcome of a rare case of gigantic fibroadenoma in a 4-year-old American Pit Bull Terrier bitch. Four firm, painless at palpation, poorly circumscribed swellings of various sizes and shapes were observed at the left hock joint and hind canon. Mixed echo pattern of the neoplasm and central large blood vessels were observed under doppler ultrasonography. The neoplasm was surgically excised with complete remission and the dog was still disease-free after 6 months. The excised tumor weighted 2350 g. Histopathological findings included; diffuse bundles of fibrous connective tissue arranged in different direction with whorl formation, sebaceous glands adenoma with cyst formation and fibroadenoma in certain areas. Tendency of malignancy was common dented by pleomorphic cells, hyperchromacia and atypical mitotic figures. Several areas of inflammatory reaction and hemorrhages were also observed within the tumor. No evidence of metastasis was seen in both chest and abdomen. In conclusion, fibroadenoma should be listed as a mixed skin neoplasm in dogs and surgical excision is curative.