Cultures from the gallbladder and blood of a 60-year-old man with acute cholecystitis grew Haemophilus aphrophilus. This organism, an unusual isolate in clinical specimens, is most frequently seen in patients with either endocarditis or brain abscesses. Haemophilus aphrophilus may be distinguished from Eikenella corrodens and Actinobacillus actinomycetemcomitans on the basis of colonial morphology and the biochemical tests for oxidase and catalase production and fermentation of lactose, sucrose, glucose, mannitol, xylose, and trehalose.