The incidence of Mycobacterium malmoense infections compared to other non-tuberculous mycobacteria (NTM) has increased since 1980, especially in northern Europe. Based on various epidemiological and clinical reports outside northern Europe, there is a wide distribution of these infections. Infections with M. malmoense cause pulmonary disease comparable with tuberculosis (TB). The main extra-pulmonary disease type is paediatric cervical lymphadenitis. M. malmoense isolates are clinically significant in about 70-80% of patients. Like other NTM infections, M. malmoense is often found in patients with chronic obstructive pulmonary disease (COPD) and may cause serious morbidity and mortality when inadequately treated. The best treatment consists of a 2-year regimen with rifampicin and ethambutol. The literature on infections with M. malmoense is reviewed with respect to epidemiology, clinical presentation, treatment and outcome.