Survival of patients with increasingly complex congenital heart disease has produced a population of children and adolescents who are susceptible to subacute bacterial endocarditis (SBE). We report a child whose endocarditis went unrecognised, and who developed amyloidosis. Asymptomatic proteinuria, haematuria and renal impairment are occasionally seen in SBE and usually indicate glomerulonephritis. Amyloidosis should also be suspected in children with long-standing bacterial endocarditis with proteinuria or other evidence of renal impairment, especially if associated with organomegaly. The diagnosis is made by renal biopsy.