Background: Psychiatric morbidity in tuberculosis (TB) patients is well-known and its impact on treatment compliance needs to be evaluated. Objectives: To study psychiatric profi le, personality trait of TB patients registered on directly observed treatment-short course (DOTS) and to evaluate their impact on treatment completion and default. Materials and Methods: Psychiatric morbidity and personality traits were assessed by Cornell Medical Index and 16PF personality questionnaire, respectively. Patients with psychiatric comorbidity were randomized into two groups. Group A: DOTS with psychiatric intervention and Group B: DOTS alone. They were followedup till treatment completion. Results: Out of 214 patients registered, 176 (82.2%) had psychiatric comorbidity. 150 (85.2%) had anxiety neurosis, and 26 (14.8%) had depression. On personality assessment, 54.1% were neurotic, 26% introverts, 15.8% extroverts, and 4.1% had other traits. Forty-one (23.3%) patients defaulted. Default rate was low (13.6 vs 33%, P = 0.002) and patient retrieval was good (67 vs 24%, P = 0.01) in group A. Patients with neurotic trait defaulted more (P = 0.006). On multivariate analysis, smoking (odds ratio (OR) = 3.76, 95% confi dence interval (CI): 1.7-8.28); alcoholism (OR = 15.4, CI: 6.67-35.72); and neurotic personality (OR = 3.54, CI: 1.61-7.79) were strongly associated with default whereas age, sex, social class, literacy, and psychiatric morbidity type were not. Conclusion: Pretreatment psychological assessment and intervention reduces default rate.