Background and Objectives: Although a significant number of Covid-19 patients tend to be hospitalized, few studies have explored the factors related to the hospitalization of these patients. This study was conducted to investigate the factors affecting the hospitalization and duration of hospitalization of the patients with Covid-19 in Shohada Imam Hossein Hospital in Tehran in the first half of 2020. Material and Methods: This cross-sectional study was performed by convenience sampling method. Data were collected using a two-part researcher-made checklist. The checklist was sent to 15 specialists in the fields of epidemiology, nursing, statistics and general practitioners to check the content validity. Content validity index (CVI) and content validity ratio (CVR) were used to check the validity of the content of the checklist and Cronbach's alpha index was used to assess the reliability. To investigate the relationship between the studied variables, independent t-test, t-test, one-way analysis of variance, Spearman and Pearson test were used at a significance level of 0. 05. Results: The Cronbach's alpha index of the study checklist was equal to (r = 0. 824). The total values of the CVI and CVR index for the whole checklist were found to be 0. 870 and 0. 733respectively. Therefore, it can be claimed that the checklist used in this study an acceptable level of content validity. 291 patients participated in this study. The mean and standard deviation of the length of hospital stay was 7. 59 ± 4. 14 days. There was a significant relationship between total length of hospital stay and each of the following variables: history of renal impairment (P-value = 0. 034), presence of symptoms of shortness of breath (P-value = 0. 007), nausea (P-value = 0. 016), oxygen therapy (P-value = 0. 022), use of Apotel (P-value = 0. 045), use of Kaltera (P-value = 0. 020), and hydroxychloroquine use (P-value = 0. 022). Conclusion: Symptoms of dyspnea, age, and oxygen therapy were the most important factors influencing the length of hospital stay. Thus, physicians and nurses should prioritize the use of oxygen therapy for patients, especially the elderly ones with the symptoms of dyspnea, in order to accelerate the recovery of the patients, and consequently reduce the duration of hospitalization.