A study was conducted at the NDTC to study 450 patients who included 225 patients who were non-cooperative in treatment. The patients were interviewed by six students from the Delhi School of Social Work and data on the patients’ socio-economic background, the period of treatment until they became irregular (those who failed to visit the clinic twice or more after repeated attempts at retrieval) or non-cooperative, their diagnosis, status at the time of their irregularity or non-cooperation, and the patients’ reasons for irregularity or non-cooperation, were filled in uniform schedules. The results and the major reasons for the patients’ irregularity and leaving treatment are presented. Measures to minimise patients’ default in treatment are recommended. Some supplementary remarks and suggestions on this study are presented by S.P. Pamra in the report on the 20th National Conference of TB and Chest Diseases Workers, Ahmedabad, India, Feb. 1965, p. 225-230.