Background/aim: Pulmonary embolism (PE) is a frequent health problem representing a diagnostic challenge with high mortality and morbidity rates. The aim of this study was to investigate the value of end-tidal carbon dioxide (ETCO2) and alveolar dead space fraction (ADSF) in the diagnosis of PE. Materials and methods: ETCO2 levels of patients with suspected PE were measured with a noninvasive mainstream sensor. ADSF of patients was calculated and PaCO2 levels were also obtained. ROC curve analysis was used to determine diagnostic values of ETCO2 and ADSF for PE. Results: The study included 159 patients. The mean values for ETCO2 and ADSF were 16.27 (95% CI, 14.52?18.03) and 0.48 (95% CI, 0.43?0.539) in the PE group and 21.57 (95% CI, 20.52?22.639) and 0.35 (95% CI, 0.32?0.38) in the non-PE group. The area under the curve (AUC) and the cut-off point for ETCO2 were found as 0.751 and ?19, with 83.8% sensitivity and 61.5% specificity. AUC and cut-off point for ADSF were found as 0.738 and >0.443, with 67.57% sensitivity and 73.77% specificity. Conclusion: The diagnostic value of calculated ADSF and noninvasive bedside ETCO2 for PE was found to be low.