One hundred twenty-eight records of patients with multiple myeloma were reviewed to assess the incidence and manifestations of liver involvement. Histologic study of the liver was available in 21 patients. Diffuse infiltration of the liver by plasma cells was observed in 10 patients, myeloid metaplasia in four, amyloidosis in two, toxic hepatitis in two, and extrahepatic cholestasis secondary to infiltration of the peripancreatic tissue by plasma cells in one. The clinical signs of plasma cell infiltration of the liver consisted of hepatomegaly in seven patients, mild elevation of liver enzymes in five, and portal hypertension in two. Jaundice was only observed in patients with hepatitis or extrahepatic cholestasis. Liver infiltration by plasma cells did not appear to have a major prognostic significance.