Background: pulmonary embolism (PE) is one of the most frequent diseases that could be missed in overcrowded emergency departments. Early and accurate diagnosis could decrease the mortality rate and this standard algorithm should be defined. Aim: The aim of this study was to evaluate the role of estimating clinical probability of pulmonary embolism and to reveal which a combination of presented clinical data that is more predictable to PE. Patients and Methods: The study included 50 patients with suspected pulmonary embolism, admitted to El Hussein and Sayed Galal University hospitals. Results: according clinical probability of patients 90% of patients from 50 cases were approved positive by CT pulmonary angio. In the current study we found that sensitivity accuracy of clinical probability in diagnosing pulmonary embolism in comparison to CT pulmonary angio was 90%. Conclusion: clinical probability of pulmonary embolism was efficient like other diagnostic methods, so biochemical parameters, clinical findings, and scoring systems, when used altogether, can contribute to the diagnosis of PE.