A subcutaneous growth developed on the left side of a zoo lion. The growth enlarged over a period of 3 months. A diagnosis of fibrosarcoma was made on account of the history, clinical and histological examinations. The lion was killed 3 weeks after surgical removal of the tumour. The autopsy showed no evidence of metastases. A foreign body (wire) was discovered in the abdominal cavity but no association was found between the lesion caused by the wire and the malignancy.