Abstract: OBJECTIVE To explore the predisposing factors, clinical manifestations, treatment outcomes and prognosis of nocardiosis so as to provide guidance for early diagnosis and treatment. METHODS The clinical data were collected from the patients who were diagnosed with nocardiosis in Tianjin First Central Hospital from Sep 2013 to Sep 2018.The predisposing factors, clinical manifestations, imaging characteristics and treatment outcomes of nocardiosis were retrospectively analyzed. RESULTS Of totally 12 patients with nocardiosis, 11（91.67%） were complicated with underlying diseases, 9（75.00%） were treated with glucocorticoids or immunosuppressors.Fever, cough and expectoration were the most common clinical manifestations.Clumps, nodules and cavities were the major imaging characteristics.The patients with pulmonary Nocardia infection were dominant among the patients with nocardiosis.The sputum specimens were the major specimens source, and there were 7（58.33%） cases of Nocardia asteroids. Five of 12 patients were complicated with fungal infection.The patients were mainly treated with sulfonamides and linezolid, and the patients who were treated with immunosuppressors and complicated with fungal infection had unfavorable treatment outcomes. CONCLUSION The immunocompromised population tends to have nocardiosis, which is more likely to be complicated with fungal infection; there was no specific clinical manifestations for nocardiosis, which may lead to misdiagnosis and missed diagnosis.