We used a descriptive analytical study. Secondary data of reported cases that meet WHO case definition of diphtheria covering from October 2017 to December 2021 at three governorates (Saadah, Al Hodeida and Dhmar) was obtained from electronic Integrated Diseases Early Warning System (eIDEWS), Variables for age, sex, district, date of onset, vaccine doses, and outcome were included. Population from Central Statistical Organization was used for calculating incidence rates (IR) per 100,000 populations, P value &amp;lt; 0.05 was used as the cutoff point for significance.