From 1960 through 1972, 236 cases of amyloidosis with histologic proof were found. The amyloidosis was primary (without evidence of preceding or coexisting disease) in 132 cases (group 1) and associated with multiple myeloma in 61 (group 2). Secondary amyloidosis appeared in 19 cases (associated with rheumatoid arthritis or osteomyelitis in two-thirds of them). There were 22 patients with amyloid localized to a single organ (bladder, lung, skin, or larynx in more than half of them). Two patients had familial amyloidosis. In group 1 and group 2, the most common presenting symptoms were fatigue, weight loss, edema, dyspnea, light-headedness or syncope, and paresthesias. Symptoms of the carpal-tunnel syndrome were frequent. The liver was palpable in almost 50% of the series, but splenomegaly was an initial finding in less than 10%. Macroglossia was recorded in 26% of group 2 and in 12% of group 1. Enlargement of submandibular structures was noted in about 10% of cases; and purpura, particularly around the eyes, was a significant feature. Substantial numbers of the patients had carpal-tunnel syndrome, nephrotic syndrome, congestive heart failure, sprue, peripheral neuropathy, or orthostatic hypotension. Approximately 50% of patients had renal insufficiency at the time of diagnosis. Proteinuria was found in more than 90%. A monoclonal protein was found in the serum of 49% of group 1 and in 74% of group 2. Monoclonal proteins were found in the urine of 35% and 81%, respectively. Only 12% of patients in group 1 had no monoclonal protein when both serum and urine were analyzed, and all patients of group 2 had a monoclonal protein in the serum or urine when both were analyzed. Lambda light chains were more common than kappa. None of the patients in group 1 had more than 15% plasma cells in the marrow, whereas more than half of group 2 had more than 15% plasma cells. Roentgenograms showed no evidence of skeletal disease in 94% of group 1, but 50% of group 2 had skeletal abnormalities. Rectal biopsy was positive for amyloid in 84% of cases. Kidney, liver, and carpal-tunnel biopsies were positive in 90% or more. Follow-up of all 193 patients in groups 1 and 2 revealed that 80% of group 1 and 97% of group 2 had died. The median survival was 14.7 months in group 1 and 4 months in group 2. Cardiac failure was the most common cause of death, accounting for 30% of the fatalities. We also reclassified all cases by the method of Isobe and Osserman (105), which is based on clinical patterns: pattern I--principal involvement of tongue, heart, gastrointestinal tract, muscle, nerves, skin, and carpal ligaments; pattern II--principal involvement of liver, spleen, kidneys, and adrenals; and mixed pattern I and II. This analysis failed to reveal predictive value in the clinical pattern classification, and did not discern the survival differences between primary amyloidosis (group 1) and amyloidosis with myeloma (group 2). Consequently, for the present we prefer the classification used in this study.