Coronavirus is a new pandemic disease that began in Wuhan, China, and has since spread over the globe. The number of COVID-19 cases reported daily in Iraq has slowly increased. This study aims to investigate the effect of Covid-19 on the normal range of White Blood Cells (WBC), D-Dimer, and Lactate Dehydrogenase (LDH). This study looked at 65 patients who had tested positive for SARS-CoV-2 using polymerase chain reaction analysis. Patients with mild symptoms and a normal CT scan for the chest were separated into three groups: those with mild symptoms and a normal CT scan for the chest, those with intermediate disease presenting with fever and cough, other respiratory symptoms, and those with severe disease. At the time of the study, all patients' data were collected from Al-Diwaniyah Teaching hospital admission for parameters of White blood cell count, lactate dehydrogenase (LDH) levels, and D-Dimer levels, from December 27, 2020, to April 1, 2021. The WBC count, D-Dimer, and LDH in the patients with COVID-19 were higher than that of the control group (8.15 X109/L versus 390 ng/ml and 593 U/L), respectively, and the difference was highly significant (p < 0.001). There was no significant difference in WBC count and LDH among patients according to the severity (p > 0.05). A larger leukocyte count, D-Dimer, and LDH increased the risk of death. These signs can reliably predict a patient's prognosis while in the hospital. Our study's best lab marker was LDH.