For a modern assessment of the clinical and morphologic features of glomerulonephritis accompanying bacterial endocarditis, postmortem and renal biopsy files were reviewed for the years 1965 to 1979, a period of changing epidemiology, etiology, and therapeutic regimens in infective endocarditis. The incidence of glomerulonephritis in 107 patients examined at postmortem was 22.4%; focal glomerulonephritis was present in 8.4%, diffuse glomerulonephritis in 14%. Glomerulonephritis occurred as frequently in acute as in subacute bacterial endocarditis. Staphylococcus aureus, which has replaced Streptococcus viridans as the predominant etiology of fatal bacterial endocarditis, was frequently associated with glomerulonephritis, especially in parenteral drug abusers. Renal functional impairment due to focal glomerulonephritis did not necessitate dialysis or contribute to the death of any patient. Presentation with advanced renal insufficiency due to diffuse glomerulonephritis was associated with both failure of antibiotic therapy to eradicate infection and failure to recover renal function. In patients with diffuse glomerulonephritis and less severe impairment of renal function, antibiotic therapy was successful in achieving bacteriologic cure, and complete recovery of renal function occurred in the majority. Features of persistent glomerular disease were frequent in patients with diffuse glomerulonephritis long after bacteriologic cure of endocarditis.