Abstract: Objective To explore the clinical characteristics of nocardiosis, deepen the understanding of this disease and improve its early diagnosis. Methods Six cases with nocardiosis admitted to Chinese PLA General Hospital from August 2009 to November 2013 were reported and the related literatures were reviewed on its risk factors, clinical manifestations, imaging features, diagnosis and treatment. Results Of the six patients, 4 were male and 2 were female with age ranging from 40 to 58. Five cases were complicated with underlying disease, interstitial pneumonia were found in 2 cases, bronchiectasis in 2 cases, diabetes mellitus in 2 cases, obsolete pulmonary tuberculosis in 1 case, UCTD in 1 case, pemphigus vulgaris in 1 case. Four patients had been treated with immunocompromised or glucocorticoids. Cough, expectoration and fever were the main clinical manifestations, others were dyspnea, fatigue and tightness. The imaging features of six cases were similar to most of pulmonary diseases on CT scanning of thorax, such as nodules, consolidation, cavity and pleural fluid. The sulfonamides-based drug therapy was the standard regimen for nocardiosis. Five patients recovered and discharged, and one patient died in hospital. Conclusion Nocardia can cause severe opportunistic infection, especially in immunocompromised patients with major risk factors. Early diagnosis is a critical step toward good prognosis.