Thrombotic events in different tissues, with consistent clinical laboratory and radiological findings, have been reported in patients with Covid-19 [5–7]. Perfusion abnormalities in lungs have been observed in patients who underwent dual-energy CTs [8]. There is also pathological evidence of the presence of platelet-fibrin thrombi in small arterial vessels in lung tissues of patients who have died of Covid-19 [9]. Based on these finding, doctors have used heparin to treat or prevent the coagulation disorder associated with the infection [5–7, 9]. This treatment can be associated with the clinical improvement of the patients, and decrease the duration of admissions and the mortality of Covid-19. Heparin is safe, economical, and easy to use, it can be given both to admitted and outpatients. However, the use of heparin in Covid-19 patients is still supported by limited evidence. This study investigates the association of the use of heparin with mortality in a large number of patients admitted with Covid-19.