We report a 59-year-old man who was found to have plasma cell dyscrasia and amyloid A protein (AA) amyloidosis during the follow-up period of chronic inactive hepatitis C. Clinical manifestations such as swallowing disturbance, proteinuria and leg edema were associated with AA amyloid deposits in his tongue and kidneys. Although the relationship between these two diseases remains to be determined, the ability of peripheral blood mononuclear cells to degradate serum amyloid A protein was apparently reduced in this patient, compared with normal volunteers. This would, in part, account for the AA amyloid deposition in this patient.