Background: Coronavirus disease 2019 (COVID-19) is frequently associated with hyponatremia. Individuals with history of chronic kidney disease (CKD) are more likely to experience critical complications related to COVID-19. Objective: This study aimed to identify the prevalence and outcomes of admittance of hyponatremia in COVID-19 patients with history of CKD. Patients and Methods: The study involved admitted CKD patients with COVID-19 between January 2021 and April 2021. It was performed at Zagazig University hospital. Subjects were divided according to admittance serum sodium into group 1 with hyponatremia (80 subjects) and group 2 with normonatremia (68 subjects). Hypernatremic patients were excluded. Clinical and laboratory data were collected from all subjects. Patients were observed for the occurrence of acute respiratory failure, and acute renal failure. Additionally, mortality rates were recorded. Results: Patients in group 1 stayed longer in the hospital than in group 2 (p = 0.034). Additionally, they had higher systolic blood pressure records (p < 0.001). Group 1 had significantly shorter survival and higher incidence rates of acute kidney injury (AKI) than group 2. Finally, multivariate analysis revealed that the significant risk factors for inhospital mortality in group 1 were older age, longer hospital stay, higher serum potassium, and higher LDH. Conclusion: In our study, hyponatremia affected 54% of CKD patients with COVID-19 and was attributed to higher rates of AKI and in-hospital mortality. Keywords: Chronic kidney diseases, COVID-19, Hyponatremia, In-Hospital mortality, Syndrome of inappropriate antidiuretic hormone secretion (SIADH).