The relationship between malnutrition and tuberculosis (TB) severity is understudied. We investigated the effect of malnutrition on radiographic findings and mycobacterial burden. Subjects included newly diagnosed, smear-positive, culture-confirmed, pulmonary TB cases enrolled in the Regional Prospective Observational Research for TB (RePORT) cohort. Multivariate regression models were used to evaluate the relationship at start of treatment between body mass index (BMI) and chest radiograph (CXR) findings of cavitation and percentage of lung affected and mycobacterial growth indicator tube (MGIT) time to positive (TTP). Severe malnutrition was defined as BMI<16 kg/m2, moderate malnutrition as 16-18.4kg/m2, and "normal"/overweight as ≥18.5 kg/m2. Of 173 TB cases with chest x-ray data, 131 (76%) were male. The median age was 45 years (range 16-82); 42 (24%) had severe malnutrition and 58 (34%) moderate malnutrition. Median percentage of lung affected was 32% (range 0-95), and 132 (76%) had cavitation. Individuals with severe malnutrition had, on average, 11.1% 95% CI: 4.0-13.3 more lung affected, compared to those with normal BMI, controlling for diabetes and cavitation. In multivariable analyses, cases with severe malnutrition had a 4.6-fold 95% CI, 1.5-14.1 increased odds of cavitation compared to those with normal BMI, controlling for smoking. Median MGIT TTP was 194.5 hours. Neither severe (aRR 0.99; 95% CI, 0.9-1.2) nor moderate (aRR 0.97; 95% CI, 0.8-1.1) malnutrition was associated with MGIT TTP. We found that malnutrition was associated with increased extent of disease and cavitation on CXR. These findings may reflect the immunomodulatory effect of malnutrition on pulmonary pathology.