Background: High rates of drug-resistant tuberculosis (DR TB) continue to threaten public health, especially in Eastern Europe. Costs for treating DR TB are substantially higher than treating drug-susceptible TB, and higher yet if DR TB services are delivered in hospital. Therefore, countries are encouraged to transition from inpatient to ambulatory-focused TB care, which has been shown to have non-inferior health outcomes. / Methods: Allocative efficiency analyses were conducted for three countries in Eastern Europe, Belarus, the Republic of Moldova, and Romania to minimise a combination of active TB cases, prevalence of active TB, and TB-related deaths by 2035. These mathematical optimisations were carried out using Optima TB, a dynamical compartmental model of TB transmission. The focus of this study was to project the health and financial gains that could be realised if TB service delivery shifted from hospital to ambulatory-based care. / Findings: These analyses show that transitioning from inpatient to ambulatory TB care could reduce treatment costs by 5%−31% or almost 35 million US dollars across these three countries without affecting the quality of care. Improved TB outcomes could be achieved without additional spending by reinvesting these potential savings in cost-effective prevention and diagnosis interventions. / Conclusions: National governments should examine barriers delaying the adoption of outpatient DR TB care and consider the lost opportunities caused by delays in switching to more efficient and effective treatment modes.