Introduction: Identifying cases that can develop to be severe at an early stage and providing appropriate therapy to patients can reduce the mortality rate in coronavirus disease 2019 (Covid-19). This study aims to determine the diagnostic value of the platelet to lymphocyte ratio (PLR) to predict case severity in Covid-19. Method: This is a prospective study. Participants of the study are patients who had been confirmed with Covid-19 based on real-time reverse transcriptase-polymerase chain reaction (rRT-PCR) who received treatment in the hospital from April to Octo- ber 2020. The sample in this study was obtained by consecutive sampling technique. A total of 507 participants were included in this study. The receiver operating characteristic curve (ROC) method is used to obtain the area under the curve (AUC), cut off value, sensitivity, and specificity of the PLR to predict case severity. Results: PLR is significantly higher in severe cases compared to mild-moderate cases (p < 0.001). The cut off value of PLR to predict severe cases of Covid-19 is more than 150 with a sensitivity of 80.5%, a specificity of 66.3%, and an area under the curve (AUC) of 0.807 (p < 0.001, 95% confidence interval (CI) 0.759 - 0.855). In binary logistic regression analysis, PLR was inde- pendently associated with case severity with the adjusted odds ratio (OR) of 7.73 (p < 0.001, 95% CI 3.75 - 15.93). Conclusions: PLR can be used as a simple and accurate biomarker to predict the case severity in Covid-19.