The Republic of Moldova is among the 30 rifampicin-resistant and/or multidrug-resistant (RR/MDR) tuberculosis (TB) high burden countries in the world. Despite free TB diagnostics and treatment, TB patients face substantial economic losses and this may impact overall treatment outcomes. We assessed if there is an association between TB-related catastrophic costs and TB treatment outcomes. We conducted a cohort study using data from patient records and a survey that quantified catastrophic costs among RR/MDR-TB affected households in the Republic of Moldova in 2016. We included adult patients (age ≥18 years) with RR/MDR-TB who had been in inpatient (intensive phase) or outpatient (continuous phase) treatment for at least 2 months. Unfavourable treatment outcome, such as failure, death or lost to follow-up, was the primary outcome variable. The definition of catastrophic TB-related costs followed the World Health Organisation (WHO) guidelines: Costs due to TB ≥20% of annual household income. Log-binomial regression was used to assess association between the outcome and catastrophic TB-related costs adjusting for other socio-demographic, behavioural and clinical covariates. In total 287 RR/MDR-TB patients (78% males, mean age 42 years) were included. Of them, 30% experienced catastrophic TB-related costs. Overall, one in five patients (21%) had unfavourable treatment outcome, such as treatment failure (5%), death (8%) or lost to follow-up (8%). The experience of catastrophic TB-related costs was not associated with unfavourable treatment outcome [adjusted relative risk (aRR)=0.88, 95% CI: 0.50-1.50]. Major factors independently associated with unfavourable TB treatment outcomes were poverty (aRR=2.07; 95% CI: 1.06-4.07), urban residence (aRR=1.99; 95% CI: 1.12- 3.52) and positive HIV (Human Immunodeficiency Virus) status (aRR=2.61; 95% CI: 1.31-4.89). As a result, we failed to find an association between catastrophic costs and treatment outcomes of RR/MDR-TB patients in the Republic of Moldova. However, we found that patients from poor households and urban areas were twice more likely to achieve unfavourable TB treatment outcomes disregarding whether they experienced catastrophic costs or not. Also, TB/HIV patients and urban residents were identified as the most vulnerable groups with higher risk of unfavourable treatment outcome and TB-related costs.