Objectives: The aim of this study is to investigate the effect of oral l-Glutamine supplementation on hospitalization time, need for intensive care unit and Coronavirus Disease-19 (Covid-19) mortality. Methods: The study included 30 Covid-19 patients using l-Glutamine and 30 Covid-19 patients who did not use l-Glutamine with similar age, gender and clinical status. Diagnostic tests, laboratory examinations, clinical findings and computed thorax tomography imaging of the patients were evaluated. Results: Hospitalization time was 10.4 +/- 1.9 days in Covid-19 without L-Glutamine group and 8.9 +/- 1.8 days in Covid-19 with L-Glutamine group (p = 0.005). In Covid-19 without the L-Glutamine group, four patients require the ICU though no one in the other group required that (p = 0.038). Only one mortality was observed in Covid-19 without the L-Glutamine group (p = 0.999). Conclusions: Nutritional supplements such as L-Glutamine boost immune system especially by inhibition of inflammatory responses. Our results suggest adding enteral L-glutamine to the normal nutrition in the early period of Covid-19 infection may lead to a shortened hospital stay and lead to less need for ICU. Larger-scale studies are needed to evaluate the effect of adding enteral L-Glutamine to the currently used treatments in the infectious diseases especially like Covid-19.