Timing of transplantation for patients with primary biliary cirrhosis (PBC) requires identification not only of individual risk factors for the operation but estimation of survival with and without transplantation. To identify those risk factors and develop a prognostic model, 82 patients grafted for PBC since 1980 in the Birmingham and Cambridge/King's College Hospital series have been analyzed. Using logrank tests it was found that treatment with diuretics, hemoglobin above 10 g/dl, prothrombin time less than 5 sec prolonged, serum sodium above 130 mmol/L and serum bilirubin less than 350 mumol/L were all individually associated with a better prognosis. Using Cox regression analysis to identify independent variables, it was found that year of transplant, serum bilirubin, serum urea, and diuretic responsive ascites had a significant association with survival. Using these four variables, it was possible to develop a model to identify those patients with a good and a poor probability of survival after transplantation.