Few studies have reported the epidemiology of lateral epicondylitis (LE) and medial epicondylitis (ME) in nationwide databases. This study aimed to investigate the epidemiology of LE and ME in South Korea. We analyzed data from the nationwide database of the Korean Health Insurance Review and Assessment Service from 2013 to 2017. We investigated the incidence, prevalence, and surgical trends in patients with LE or ME. Between 2013 and 2017, we identified 2813,431 and 836,610 patients with LE and ME, respectively. LE and ME were more frequently diagnosed in women than in men. During the study period, the mean annual age-adjusted incidence rates of LE and ME were 9.7 per 1000 people and 2.9 per 1000 people, respectively. The incidence of LE did not change significantly during the study period, but the prevalence rate increased significantly. Conversely, the incidence and prevalence rates of ME have significantly increased. Furthermore, 0.8% and 1.0% of patients with LE and ME, respectively, required surgical treatment, showing an annual increase in the number of surgical treatments for LE and ME, respectively. The proportion of arthroscopic surgeries performed for LE did not significantly change during the study period. The prevalence of LE and ME has increased in South Korea. Consequently, the number of surgeries performed annually for LE and ME has increased.