Background: TB detection rate remains critical stumbling block for TB control. Thoughrnconventional methods for TB detection exist; GeneXpert MTB/RIF assay represents a paradigmrnshift in the diagnosis of TB and MDR-TB by simultaneous detection of M.tuberculosis andrnrifampicin resistance bacilli. However information regarding the performance characteristics ofrnXpert MTB/RIF assay is scarce in Ethiopia.rnObjective: To evaluate the performance of Xpert MTB/RIF assay for diagnosis of pulmonaryrntuberculosis and detection of Rifampicin resistance in sputum specimens at Karamara hospital,rnJigjiga.rnMaterials and methods: A total of 227 paired expectorated sputum samples from patients withrnsigns and symptoms of suggestive of tuberculosis at Karamara hospital during February 2014 tornMay 2014 were recruited by consecutive sampling method. Sputum sample was tested directlyrnby Ziehl-Neelsen staining and Xpert MTB/RIF assay without NALC-NaOH decontaminationrnand sputum samples were cultured for isolation and drug sensitivity testing of TB bacilli.rnDiagnostic performance of Xpert MTB/RIF assay and AFB smear microscopy was calculatedrnusing sensitivity, specificity, positive and negative predictive values, positive and negativernlikelihood ratios against culture as the gold standard. Results with contaminated cultures (forrnboth LJ and MGIT) and failed Xpert MTB/RIF were excluded from analysis.rnResults: Overall 25.5% (58/227) samples were positive for MTBC by MGIT and/or LJ media ofrnwhich 36.2 % (21/58) and 65.5% (35/58) were positive by AFB smear microscopy and XpertrnMTB/RIF respectively. The sensitivity, specificity, positive and negative predictive value ofrnXpert MTB/RIF assay were 65.5% (95% CI: 53.3-77.7%), 96.3% (95% CI: 93.4-99.2%), 86.4%rn(95% CI: 76.2-96.5%), and 88.6% (95% CI: 83.9-93.3%) respectively. Eighteen (31.0%, 18/58)rnmore cases, which were smear microscopy negative, were detected by Xpert MTB/RIF assayrnConclusion: Xpert MTB/RIF assay demonstrated high sensitivity in detecting MTBC in sputumrnspecimens compared with conventional AFB smear microscopy. However, it demonstratedrnsuboptimal sensitivity in smear negative patients compared to culture test.rnKeywords: Xpert MTB/RIF assay, NPV, PPV, Sensitivity, Specificity