Objective: We aimed to evaluate the degree of QTc prolongation and associated factors in patients with COVID-19 in association with their usage of hydroxychloroquine (HCQ) with or without the combination of azithromycin (AZ) and/or favipiravir (FAV). Methods: This single-center, retrospective study was conducted in a tertiary care university hospital. We retrospectively examined the pre- and post-treatment electrocardiogram (ECG) records of 74 patients. Results: The median age was 44 (interquartile range [IQR] 27), and 34 (45.5%) of them were women. All these 74 patients were treated with HCQ. Sixty-three of them (83.2%) were treated with AZ, and eight patients (10.8%) also were treated with plus favipiravir. All ECGs were in sinus rhythm, and arrhythmia was not developed in any patients. The median (IQR) baseline QTc of 74 patients was 400 (375- 421) milliseconds, the median (IQR) post-treatment QTc was 418 milliseconds (391-432), and the change was statistically significant (P < .001). There was no statistically significant difference in QTc prolongation between treatment groups. In the linear regression model, moderate disease activity, higher Modified Early Warning Score (MEWS) score ( 2), and heart rate were independent predictors. QTc prolongation of more than 60 milliseconds was observed in five patients (6.7%). Post-treatment QTc value of over 500 milliseconds was observed in three patients (4%), and the drugs were discontinued. Conclusions: This is the first study that demonstrates that MEWS score and disease severity are related to higher QTc prolongation values. HCQ, AZ, and FAV should be safely used in patients with lower MEWS score and without the severe disease, in conjunction with QTc follow-up.