Evaluating the outcomes of DOTS program is essential for recognizing and amending system failures before the incidence and proportion of resistant isolates rise. In this study, we seek to evaluate the impact of DOTS strategy on tuberculosis treatment success rate in Dabat, northwest Ethiopia. Medical records of 1305 pulmonary and extrapulmonary tuberculosis patients registered from 2007 to 2012 at two health centers in Dabat district, northwest Ethiopia, were reviewed. Treatment outcomes and forms of tuberculosis were assessed according to WHO guidelines. Descriptive analyses were performed using frequencies and percentages. Treatment success rate was observed in 1146 (87.8%) patients. Out of these, 534 (89.1%) of the males and 612 (86.7%) of the females were successfully treated. It was also true in 338 (87.8%) of the smear-positive pulmonary tuberculosis patients, 473 (85.7%) of the smear-negative pulmonary tuberculosis patients, and 335 (91.0%) of the extrapulmonary tuberculosis patients. In conclusion, treatment success rate in the current study was slightly higher than the WHO international updated target for the period 2011 to 2015. However, this doesn’t mean that there will be no need for further enhancement of supervision and monitoring techniques, strengthening counseling and health education programs, and improving the quality of laboratory diagnostic services.