Treatment failure in patients with pulmonary tuberculosis poses a great danger to the global effort in control of tuberculosis. This study evaluated prevalence of treatment failure among pulmonary tuberculosis patients at Federal Medical Centre (FMC) Gombe, Nigeria. Consecutive patients managed between August 2008 and August 2009 at the Directly Observed Therapy (Tuberculosis) Unit of our hospital were enrolled for the study. Sputum specimens were collected from each patient at entry for Acid Fast Bacilli and repeated at the end of 2nd, 5th and 7th month of treatment. Of the 247 patients recruited, 200 patients consisting of 118 (59%) males and 82 (41%) females aged 15–78 years with a mean of 36.8 ± 12.4 years completed the study. One hundred and fifteen (57.5%) of the patients were sputum smear positive at entry while 85 (42%) were negative. Among 115 smear positive patients at baseline, 80 patients (69.6%), 26 (22.6%) and 24 (20.9%) remained positive after 2nd, 5th and 7th month of treatment respectively. In conclusion, there is a high treatment failure rate (22.6%) among our TB patients; and this poses a great danger to healthcare personnel and close contacts in the community.