Treatment non-adherence fuels continuing TB transmission and fosters the development of drug resistance, resulting in serious risks both for the individual patient and for the community: the objective of study were To assess the determinant factors of defaulting TB treatment. Unmatched case control study design was conducted. Here the cases are those TB patients who default the treatment of anti- TB drug in TB clinics during the study period and controls are those patients of adherence of ant- TB. For each case, there was one control. Simple random sampling was used. By using structured questionnaire and secondary data the data was collected by trained data collector. The date was collected from May 1-30/12/2013 G.C. The most frequent reasons for default identified were included increased family size , low income , occupation status, religion believe , inadequate knowledge and perception about TB , unawareness of TB treatment, having experience of stigmatization . Predictive factors for default were inadequate knowledge about TB treatment period, housing status and having experience of stigmatization.