To determine the extent and causes of Fall-out (premature abandonment of chemotherapy) and Irregularities (chemotherapy continued with interruption), 1,274 TB cases registered at the domiciliary treatment section of the Chest Department, Medical College, Calcutta, were accepted for study. Among 668 who stopped attending the clinic, 277 (21.74%) fell-out (most fell-out within the first 3 months suggesting that home visits and other efforts for patient recall should be intensified at this time). After quiescence of lesions and stoppage of chemotherapy, 21.28% (of 329 cases) fell-out during a follow-up of 1-7 years, with the trend showing an increase in fall-out with time. The Irregulars who had at least 3 months of treatment (854 cases) were defined as Major and, Minor and Regular cases. Comparative studies of these two groups with regard to several factors revealed that the Irregulars fared much worse than the Regulars except in the group with minimal (extent I) lesions. Suggestions are offered to decrease the above problems.