A report is presented on the findings in what is to our knowledge the first described case of glomerulonephritis resulting from Haemophilus aphrophilus endocarditis. After an insidious onset, serious renal failure developed which subsided with antibiotic therapy. Cardiac damage was minimal and the patient recovered his usual state of health, an outcome which has not been so satisfactory in other reported cases of endocarditis due to Haemophilus aphrophilus. The case is discussed with reference to the clinical course of the disease and the microbiologic properties of Haemophilus aphrophilus.