A case of malignant schwannoma of the sciatic nerve is described associated with hepatic dysfunction in the absence of hepatic metastases. An elevated serum alkaline phosphatase activity was present with an isoenzyme pattern indicating hepatic involvement. These abnormalities disappeared after extirpation of the tumour. The patient is well, with no evidence of metastases, over two years later. It is concluded that the abnormality of serum alkaline phosphatase was induced by the tumour, and that the liver can be involved in the paraneoplastic syndrome.