Congenital factor X (FX) deficiency is an extremely rare, bleeding disorder with an estimated incidence of one per 1 million. Patients with severe FX deficiency (FX:C < 1%) demonstrate a wide spectrum of serious clinical presentations, including hemarthrosis, hematoma, gastrointestinal (GI) bleeding, intracranial hemorrhage (ICH), and umbilical cord bleeding. 1 In fact, severe FX deficiency, with a high rate of life-threatening bleeding, is the second-most severe, rare coagulation factor deficiency (RCFD) after FXIII deficiency. 1,2 Although homozygotes are at risk of severe bleeding, heterozygotes usually are asymptomatic, but postsurgical bleeding or bleeding after childbirth may occur. 1,2 Other risk factors can increase the risk of bleeding in FX deficiency, and coronavirus disease 2019 (COVID-19), a new medical challenge, could affect the patient's bleeding or thrombotic tendency. 3 COVID-19, which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) presents an enormous challenge for everyone, especially for those with underlying risk factors such as cardiovascular disease, diabetes, obesity, and renal failure. Age and male sex are other risk factors. 4 Limited data are available regarding the effect of COVID-19 on patients with congenital bleeding disorders (CBDs), particularly RCFDs. 5 It has been shown that hypercoagulability-related adverse consequences are less common among patients with CBDs, at least in those with moderate-to-severe deficiency, but further studies, including our ongoing work on a large number of patients, are required. 5 Although there are several