Two cases of chronic and apparently inflammatory bone and lung disease are presented in which the offending organisms are thought to be atypical mycobacteria. Scotochromogens were found in smears and cultures of material obtained from the bone lesions and gastric washings. The patients had features which appear to be characteristic of infections due to atypical mycobacteria, i.e., paucity of symptoms, poor response to antituberculosis therapy, and chronicity. The two cases strongly suggest that these organisms have the ability to cause bone disease. It is felt that awareness of this possibility will probably uncover other cases in which the demonstration of “yellow” acid-fast bacilli would otherwise be attributed to accidental contamination.