Abstract: Objective: To attempt in improving the early diagnosis of nocardiosis. Methods: Two cases with nocardiosis confirmed by seperating nocardia asteroides were reported and the allied literatures were reviewed on the high risk factors, clinical features, diagnosis, prognosis and treatment of nocardiosis. Results: The two patients had the basic diseases of nephrotic syndrome （NS） and systemic lupus erythematosus and had used steroids for a long term before admission. And both of them were also complicated with cerebral abscess. The first case did not use sulphadiazine （SD） because of his NS. The second case used the SD, but interrupted as renal poisoning developed. Both cases died. Conclusion: The isolation and determination of nocardia asteroides is the funtamental tool for early diagnosis of nocardiosis. The sulfonamide is the first line drug for treatment, but renal toxicity should be watched carefully. The prognosis will be very bad if accompanied with cerebral absess.