The typical test for diagnosis of severe acute respiratory syndrome coronavirus 2 is a reverse transcription-polymerase chain reaction (RT-PCR) technique, but the chest CT scan might play a complementary role at the first detection of Coronavirus Disease 2019 (COVID-19) pneumonia. Objectives: To determine the sensitivity of CT scan on patients with COVID-19 in Al-Najaf, Iraq, and to compare the accuracy of CT scan with that of RT-PCR technique. Material and Method: This is a prospective study. The patients suspicious of having COVID-19 infection and respiratory symptoms were registered. All patients were diagnosed by RT-PCR and chest CT. Diagnostic performance of CT was intended using RT-PCR as the reference standard in the centre of coronavirus investigation in Al-Najaf city, Iraq from March 2020 to September 2020. Results: The study population included 125 consecutive participants (males and females; mean age = 53 ± 17 years). Of the 125 participants, fever was observed in 93 (74.4%), cough was observed in 81 (64.8%), dyspnoea was observed in 47 (33%), and lymphocytopenia was observed in 89 (71.2%) subjects. The sensitivity and specificity of chest CT scan was 94% (95% confidence interval). Conclusion: The typical diagnosis of Coronavirus Disease 2019 pneumonia is by RT-PCR at the first stage of infection which can then be confirmed by chest CT.