Four patients underwent liver transplantation in the Cambridge/King's College Hospital programme for malignant primary and secondary apudomas, secreting various peptide hormones and uncontrollable by standard treatment techniques. After transplantation all patients had excellent symptomatic relief and specific peptide hormone levels fell to normal ranges. Two patients remain alive and well after 38 and 22 months, the latter with recurrence of slight tumour-related symptoms and elevation of the specific secretory product. The other two patients died from chronic graft rejection 7 and 8 months after transplantation.