Mycobacterium simiae is commonly found in nature and its role as a pathogen has been controversial. A case of disseminated M. simiae infection with blood, pulmonary and cutaneous localization is reported here. The pathogenic role of M. simiae was clearly demonstrated as it was the only organism isolated from sputum, broncho-alveolar lavage fluid, as well as blood and skin tissue. Identification of M. simiae by conventional testing may be difficult. Analysis of fatty and mycolic acid patterns, as performed in this case, is necessary to confirm its identification.