Background: It is possible to predict the severity of COVID-19 based on the platelet-to-lymphocyte ratio (PLR), which is a novel biomarker. Objective: This study was aimed to evaluate the correlation between PLR levels and the severity of COVID-19 patients in Zagazig University Hospital. Patients and Methods: At Zagazig University Hospitals' Isolation Hospital, a comparative cross-sectional study was conducted on 48 confirmed COVID-19 patients over the age of 18 of both sexes. Patients were categorized into two groups based on the severity of their symptoms (mild and severe) At least one of the following criteria was met by very ill patients: 1- Oxygen saturation is below 93% in the resting condition. 2- Breathing difficulty, RR equal or higher than 30 times/min. All patients underwent a laboratory investigations with assessment of PLR. Results: A higher platelet count/lymphocyte ratio was not related with more severe disease since the median in severe cases (197.31) was somewhat higher than the median in mild cases (184.72) with non-statistically significant differences. Our study proved a strong correlation between a decrease in platelet count and the severity of illness. Because of its low AUC of 0.559, PLR was ruled out as a diagnostic biomarker that might be used to predict the severity of disease. The optimal cut-off value was ≥ 5.1464, sensitivity was 60%, specificity was 55.6%, positive predictive value (PPV) was 69.2%, negative predictive value (NPV) was 45.5% and its accuracy was 58.3% (p>0.05). Conclusion: PLR could not be used as a potential diagnostic marker for COVID 19 disease severity.