Negative conversion of pulmonary tuberculous bacilli is determined by using a discharge standard. The primary goal of tuberculosis treatment is early negative conversion of bacilli. Nutritional factors upon admission that might predict a delay in negative bacillary conversion were investigated. The study cohort comprised 554 inpatients who were treated for pulmonary tuberculosis between April 2005 and March 2007 at the National Hospital Organization Kinki-chuo Chest Medical Center. Factors that might delay negative conversion that were investigated included: age, sex, body mass index (BMI), serum albumin (Alb), C-reactive protein (CRP), hemoglobin A1c (HbA1c), hospital meal intake, percent of recommended dietary allowance of energy (RDA ％ energy), percent of recommended dietary allowance of protein (RDA ％ protein), and sputum smear test. Variables were entered into a univariable log-rank test and multivariate regression analysis was performed. Univariate analysis yielded the following hospitalization nourishment factors associated with a delay in negative conversion: male gender, BMI ＜18.5kg/m², Alb ≦3.0g/dL, CRP ≧0.3 mg/dL, HbA1c ≧6.5%, RDA ％ energy ＜87％, and sputum smear test 2＋～3＋. Multivariate regression analysis yielded the following hospitalization nourishment factors that were associated with a significant delay in negative conversion: HbA1c, CRP, and BMI. Nutritional assessment of patients with pulmonary tuberculosis indicated that HbA1c, CRP, and BMI could be used to predict a delay in negative conversion.