Multidrug-resistant tuberculosis (MDR-TB) is a serious obstacle to TB control [1]. The disproportionately negative outcomes among patients with drug resistance reflect a strong global need to develop new anti-TB drugs [2, 3]. Delamanid is a novel anti-TB agent that has recently been approved for the management of MDR-TB patients [4]. Treatment of MDR-TB patients with delamanid in combination with an optimised background regimen for 2 months significantly improved 2-month sputum culture conversion (SCC) by ~50%, in comparison to treatment with placebo plus an optimised background regimen [5]. Additionally, compared to ≤2 months of treatment, ≥6 months of treatment with delamanid plus an optimised background regimen was associated with higher favourable treatment outcomes (55.0% versus 74.5%) and significantly lower mortality (8.3% versus 1.0%, p<0.001) [6]. While early SCC is recognised as a biomarker in the development of anti-TB drugs [7–9], the impact of early SCC on long-term mortality in MDR-TB patients has only been assessed in retrospective cohort analyses [10–13]. Using updated prospective data from the delamanid development programme, we assessed the association between 2-month SCC and mortality in MDR-TB patients and expanded a previous analysis on the impact of long-term treatment with delamanid on mortality.