The aim of this work is to study the usage of multi-detector HRCT chest in diagnosing pulmonary TB cases whose sputum smears are negative and making a correlation between their CT features and their sputum culture results. This study was carried out from December 2014 to December 2016 at Zagazig university hospitals, Radiodiagnosis department. It included 150 patients. Their ages ranged between 10 to 70 years with a mean age 40 years. They were referred from the outpatient respiratory medicine clinic of the hospital. All patients had been presented clinically with suspicion of PTB. Their clinical features and HRCT findings were investigated to predict the risk for PTB. We then designed provisional HRCT diagnostic criteria based on the results to rank the risk of PTB. A positive tuberculin skin test alone among clinical laboratory findings was significantly associated with an increase of risk of PTB. Centrilobular nodules, large nodules, tree-in-bud appearance and the main lesion being located in S1, S2, and S6 lung segments were significantly associated with an increased risk of PTB. At HRCT 40 out of 44 patients with class III ranking showed active pulmonary TB. 12 out of 51 patients presented with class II ranking and 8 out of 40 were ranked as class I. The sensitivity, specificity and positive likelihood ratio of class I ranking HRCT criteria to diagnose active pulmonary TB were 95%, 40% and 1.4, respectively. Class II ranking results were 85%, 72%, 3, respectively. Finally class III ranking results were 45%, 90%, 11.5, respectively. Cases suspected of having active pulmonary TB whose smears are negative can benefit from MD HRCT chest findings to predict those patients of high risk with good reproducibility.