Forty-three of the chest wall tumours in 46 dogs were malignant; five had metastases apparent at the time of presentation, five more had metastases discovered intraoperatively. Surgical resection of the tumours was associated with a significantly better outcome than conservative management. The median survival times after surgery for dogs with osteosarcoma was 17 weeks, for dogs with fibrosarcoma it was 26 weeks and for dogs with chondrosarcoma it was 250 weeks. En bloc excision of primary tumours affecting the chest wall was associated with minimal morbidity, but long-term survival was limited by distant metastases, primarily to the lungs. The tumours recurred in only three dogs. Early, radical surgical excision is recommended in the management of tumours of the chest wall. The prognosis depends on the histologic type of tumour and a histological diagnosis is mandatory before excision.