The prevalence of pulmonary nocardiosis in a tuberculosis and chest diseases hospital in Amritsar is reported. Of 1510 sputum samples cultured from 1016 patients, 67 sputa originating from 16 patients were found to be positive for the Nocardia asteroides species complex. Based upon repeated isolation of N. asteroides from the respiratory tract, its microscopic demonstration in KOH wet mounts or stained smears of sputum and clinical evaluation of patients, 14 cases of pulmonary nocardiosis were diagnosed. This gave a prevalence of 1.4% pulmonary nocardiosis in the tuberculosis hospital. The prevalence of the disease was found to be 1.3% in the males as against 1.5% in the females. Of the various clinical categories of patients investigated, pulmonary tuberculosis with sputum negative for acid-fast bacilli (AFB) yielded the highest prevalence of 3.2%, followed by 1.3%, 1.2%, 1.1% and 0.5% in pneumonia, chronic obstructive pulmonary disease (COPD), bronchiectasis and pulmonary tuberculosis with sputum positive for AFB, respectively. Type IV cutaneous hypersensitivity to nocardin was observed in 19 of 908 (2%) patients tested, whereas only a solitary positive reactor was found among 260 healthy volunteers. Twelve of 19 nocardin positive reactors (63%) had unequivocally proven pulmonary nocardiosis. The nocardin skin test gave false negative results in two nocardiosis patients. More comprehensive investigations are warranted in order to evaluate the nocardin skin test as an additional aid for the diagnosis of nocardiosis. Barring a solitary exception, the nocardiosis patients were successfully treated with sulphadiazine or trimethoprim-sulphamethoxazole (TMP-SMZ) combination. To the best of our knowledge, this is the largest series of pulmonary nocardiosis patients in a prospective study as yet reported from India. The observations underscore the point that nocardiosis warrants greater attention in the differential diagnosis of bronchopulmonary diseases.