Background:The treatment outcome “default” under Revised National Tuberculosis Control Program (RNTCP) is a patient who after treatment initiation has interrupted treatment consecutively for more than 2 months.Aims:To assess the timing, characteristics and distribution of the reasons for default with relation to some sociodemographic variables among new sputum-positive (NSP) tuberculosis (TB) patients in Darjeeling District, West Bengal.Settings and Design:A case-control study was conducted in three tuberculosis units (TUs) of Darjeeling from August’2011 to December’2011 among NSP TB patients enrolled for treatment in the TB register from 1st Qtr’09 to 2nd Qtr’10. Patients defaulted from treatment were considered as “cases” and those completed treatment as “controls” (79 cases and 79 controls).Materials and Methods:The enrolled cases and controls were interviewed by the health workers using a predesigned structured pro-forma.Statistical Analysis Used:Logistic regression analysis, odds ratios (OR), adjusted odds ratios (AOR).Results:75% of the default occurred in the intensive phase (IP); 54.24% retrieval action was done within 1 day during IP and 75% within 1 week during continuation phase (CP); cent percent of the documented retrieval actions were undertaken by the contractual TB program staffs. Most commonly cited reasons for default were alcohol consumption (29.11%), adverse effects of drugs (25.32%), and long distance of DOT center (21.52%). In the logistic regression analysis, the factors independently associated were consumption of alcohol, inadequate knowledge about TB, inadequate patient provider interaction, instances of missed doses, adverse reactions of anti-TB drugs, Government Directly Observed Treatment (DOT) provider and smoking.Conclusions:Most defaults occurred in the intensive phase; pre-treatment counseling and initial home visit play very important role in this regard. Proper counseling by health care workers in patient provider meeting is needed.