Introduction: Tuberculosis (TB) represents a global epidemic and causes significant mortality mostly in developing countries. With the emergence of HIV pandemic the steady decline in the incidence of tuberculosis was halted in developed countries and in fact it is reversed. Similarly an epidemic of diabetes mellitus is sweeping the country. Aims and Objectives: Isolation of Mycobacterium tuberculosis on solid media from different groups like HIV/AIDS patients, Diabetics, immunocompetent persons and to study the isolation rates in smear negative suspected cases. Materials and Methods: This study was performed on sputum of tuberculosis suspected patients from different risk groups. All the specimens were examined microscopically by using Ziehl-Neelsen's staining and decontamination was performed using Modified Petroffs technique. The decontaminated deposit was cultured on LJ slopes. Results: Out of a total of 50 HIV positive cases, 25 diabetic cases and 25 immunocompetent persons with suspected tuberculosis 44%, 8% and 68% were found to be co-infected with tuberculosis. Out of total of 100 cases of symptomatic pulmonary tuberculosis, 34 (34%) were sputum positive and 66 (66%) were sputum negative. Maximum no. of sputum positive cases are among symptomatic immunocompetent persons (60%) followed by HIV positive cases (34%) and Diabetics (8%). All the strains isolated were identified as Mycobacterium tuberculosis and no non-tuberculous mycobacteria spp (NTM) were isolated. Conclusion: Conventional culture technique is the gold standard for diagnosis of pulmonary tuberculosis. Priority for tuberculosis control remains early detection and effective treatment of active cases of tuberculosis.