Nondiphtherial Corynebacterium species isolated from clinical specimens are usually considered as contaminants by many clinicians when reported by microbiologists. However, an increasing number of studies have confirmed the importance of Corynebacterium spp. in the etiology of a variety of infectious processes. In this report, we present a case of bronchopneumonia caused by Corynebacterium propinquum. The infection occurred in a seven-year-old child who had a history of immunosuppression due to ataxia telangiectasia. The purulent sputum of the patient yielded a large number of polymorphonuclear leucocytes with abundant gram-positive coryneform bacilli in gram staining and pure growth of coryneform bacteria in culture. Definitive identification as C. propinquum was made by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and 16S rRNA gene sequencing. C. propinquum should be recognized as a potential pathogen and included in the etiologic diagnostic algorithm, particularly in patients with immunosuppressive conditions.