The morphological and clinical findings in 122 patients with renal amyloidosis proved by renal biopsy were studied. A higher incidence of amyloidosis occurred in males than females. Coexisting disorders in addition to amyloidosis were present in 80% of the patients. The nephrotic syndrome was a main clinical feature. No significant differences were observed in the manifestations of amyloid renal disease among patients with primary and secondary amyloidosis. Amyloid deposition was present in the mesangium and along the basement membrane. The glomerular basement membrane was damaged by the accumulation of amyloid. The amounts of amyloid in the glomeruli correlated roughly with the clinical manifestations of the disease. The formation of new basement membrane-like substance and the occurrence of granulomatous reaction against amyloid deposits were discussed in relation to the course of hte disease.