Moraxella catarrhalis rarely causes severe infections or bacteraemia in healthy subjects. In the literature only four cases of clinical sepsis with M. catarrhalis have been described, mostly in immunocompromised patients. We describe a case of a 34-year-old patient with Kugelberg-Welander disease and low body weight (28 kg) who developed clinical sepsis due to M. catarrhalis bacteraemia. A review of the literature is given.