Streptococcus constellatus is a germ that belongs to the Streptococcus milleri group, it has a particular tropism for the digestive tract and the hepatobiliary region. It is found in deep abscesses in immunocompromised patients. 70-year-old patient admitted to the emergency room for a pain in the right iliac fossa. The abdominal scan showed a retro cecal collection probably related to an appendicular abscess. The cytobacteriological study of abscess sampling in peroperatively demonstrated the presence of Streptococcus constellatus associated with Escherichia coli. The identification of a streptococcus of the milleri group is difficult by ordinary methods and must make search for an abscess.