Tehran University of Medical Sciences Frontiers in Emergency Medicine 2717-3593 3 4 2019 08 29 e49 e49 Ahmed Negida Faculty of Medicine, Zagazig University, Zagazig, El-Sharkia, Egypt. Nadien Fahim Clinical Program, Faculty of Pharmacy, Zagazig University, Zagazig, Egypt Yasmin Negida Faculty of Medicine, Zagazig University, Zagazig, El-Sharkia, Egypt Hussien Ahmed Faculty of Medicine, Zagazig University, Zagazig, El-Sharkia, Egypt. 2019 08 29 In the previous educational articles, we explained how to calculate the sample size for a rate or a single proportion, for an independent cohort study, for an independent case-control study, and for a diagnostic test accuracy study. In this article, we explain how to calculate the sample size for a superiority clinical trial. https://fem.tums.ac.ir/index.php/fem/article/view/255 https://fem.tums.ac.ir/index.php/fem/article/download/255/214