Nocardiosis is an acute, subacute or chronic infection, which usually introduced through the respiratory tract resulting pneumonia, and may develop a disseminated infection, especially subcutaneous abscess and/or CNS infection. It is usually affects the immunocompromized host and may be fatal unless early diagnosis and adequate treatment are performed. There have been only several case reports of nocardial infection in Korea. Nocardiosis is so unfamiliar to many physicians that may be misdiagnosed as pneumonia, tuberculosis, or neoplasm. We have experienced a case of nocardiosis from a patient who had been treated as pneumonia and tuberculosis at first. The 57-year-old male patient had fever, chill, dyspnea and blood tinged purulent sputum for 20 days. Under the impression of bacterial pneumonia, broad spectrum antibiotics were administered for more than 3 weeks without clinical improvement. Although antituberculous drugs began to be administered after acid fast bacilli were found in bronchial aspirate by bronchoscopy, the nocardial infection was suspected due to no clinical response toward antituberculous therapy and the occurrence of multiple subcutaneous abscesses on scalp. The diagnosis was made by modified Ziehl-Neelson stain and culture of the sputum and pus. Nocardia asteroides was identified. After 25 days of trimethoprim-sulfamethoxazole treatment, the patient was much improved and discharged.