Tuberculosis (TB) and malnutrition co-exist. Malnutrition predisposes to development of TB, and may further predict treatment outcomes. Given that paucity of data regarding malnutrition in specific populations with multidrugresistant (MDR)-TB, we aimed to determine the pre-treatment and post-treatment change in nutrition status, as measured by body mass index (BMI), in patients from Tanzania initiating MDR-TB treatment, as well as potentially modifiable determinants of BMI in this population at high-risk for treatment failure.