The goal was to identify and measure factors associated with DOT failure and default, in order to suggest suitable measures to increase the treatment success rate. The study was designed to examine qualitatively and quantitatively the factors associated with TB defaults and failures. The goal of the quantitative part of the study was to identify and measure factors associated with DOT failure and default, in order to suggest suitable measures to increase the treatment success rate. A case-control study was conducted in patients with new pulmonary smear-positive active TB case registered between January 1, 2006 - March 31, 2007, who have started treatment for TB with known or unknown outcome. The study sample consisted of 99 cases and 198 controls matched by sex and age. The study measured major risk factors including factors associated to onset of TB, model of TB care, communications between patient and physicians and patient knowledge; personal and economic factors. The qualitative study explores the opinion of providers (primary health care and TB specialists) on factors associated with poor treatment outcomes.