Background & objectives: In spite of the high prevalence of tuberculosis worldwide, there are only a few studies on its psychiatric complications such as suicidal behaviour. We undertook this study to assess the prevalence of suicidal behaviour and its associated factors among tuberculosis patients in public primary care in South Africa. Methods: In a cross-sectional survey conducted in three provinces of South Africa new TB and new re-treatment patients were assessed within one month of anti-tuberculosis treatment. The sample included 4900 (54.5% men and women 45.5%) consecutively selected tuberculosis patients from 42 public primary care clinics in three districts in South Africa. Results: A total of 322 patients (9.0%) reported suicidal ideation and 131 (3.1%) had a history of a suicide attempt. In multivariate analysis female gender [Odds Ratio (OR)= 0.56, Confidence Interval (CI)= 0.43-0.74], psychological distress (OR=2.36, CI=1.04-2.29), post-traumatic stress disorders (PTSD) (OR=4.98, CI=3.76-6.59), harmful alcohol use (OR=1.97, CI=1.25-3.09) and being a TB re-treatment patient (OR=1.76, CI=1.32-2.34) were associated with suicidal ideation, and psychological distress (OR=3.27, CI=1.51-7.10), PTSD symptoms (OR=4.48, CI=3.04-6.61) and harmful alcohol use (OR=3.01, CI=1.83-4.95) were associated with a suicide attempt. Interpretation & conclusions: Our findings suggest that co-morbid illnesses of psychological distress, PTSD and harmful alcohol use and HIV infection should be assessed in TB patients under TB control programmes to prevent suicidal behaviour. Clinicians should be aware about suicidality in tuberculosis patients to reduce mortality.