B A C K G R O U N D: Treating multidrug-resistant TB (MDR-TB) remains challenging. However, the determinants and timing of poor outcomes during MDR-TB treatment are still poorly understood. M E T H O D S: We conducted a retrospective cohort study on all adult MDR-TB patients treated at Persahabatan Hospital, Jakarta, Indonesia, between January 2013 and December 2016. Risk factors for poor outcomes were analysed using Cox regression. R E S U LT S: Death occurred at a median time of 6 months (IQR 4–14) and loss to follow-up (LTFU) at 7 months (IQR 3–11). In multivariate analysis, advanced age (aHR 2.91, 95% CI 1.21–6.96; P ¼ 0.017 for age .60 years), having diabetes mellitus (aHR 2.18, 95% CI 1.25–3.82; P ¼ 0.006) and HIV co-infection (aHR 3.73, 95% CI 1.14–12.23; P ¼ 0.030) were predictive of poor outcome in the first 7 months of treatment, whereas history of LTFU (patients who were LTFU once: aHR 2.14, 95% CI 1.33–3.47; P ¼ 0.002; patients who were LTFU more than once: aHR 3.61, 95% CI 1.68–7.77; P ¼ 0.001) and baseline body mass index,18.5 kg/m2 (aHR 1.98, 95% CI 1.10–3.56; P ¼ 0.022) predicted poor outcome after 7 months of treatment. C O N C L U S I O N: Different subsets of patients with MDR-TB are at risk of poor outcome at different times during treatment. Q 2022 The Union.