This study investigated the response rate and toxicity of blood cell transplantation as treatment for primary amyloidosis (AL). Twenty-three patients had stem cells collected between November 1995 and September 1998. Conditioning included melphalan and total body irradiation in 16 and melphalan alone in 4. Three patients did not undergo stem cell infusion because of poor performance status. Two died of progressive amyloid at 1 and 3 months. One patient is alive on hemodialysis. Fourteen males and six females (median age, 57 years) underwent transplantation. Renal, cardiac (by echocardiography), peripheral neuropathy or liver amyloidosis occurred in 14, 12, 3, and 1, respectively. Echocardiography demonstrated an interventricular septal thickness > or = 15 mm in six patients, five of whom died post transplantation. Three patients died of progressive amyloidosis at 7, 7, and 21 months. Thirteen patients are alive with a follow-up of 3 to 26 months. Twelve (60%) fulfilled the criteria of a hematologic or organ response. Severe gastrointestinal tract toxicity was seen in five (25%). We conclude that blood cell transplantation for amyloidosis had a much higher morbidity and mortality compared with transplantation for myeloma. The best results appear to occur in patients with nephrotic syndrome as the only manifestation of their disease.