Owing to the rarity of the disease, epidemiologic information on achalasia is limited. This study aimed to investigate the epidemiology and treatment patterns of achalasia in the population of Korea using a national healthcare database. The diagnostic code K22.0 of the International Classification of Diseases was used to identify cases of achalasia between 2007 and 2011. Treatment modalities for achalasia were identified using the electronic data interchange codes Q7642 or Q7641 for balloon dilation and QA421 or QA422 for esophago-cardiomyotomy. A total of 3,105 patients with achalasia (1,447 men; mean age, 52.5 yr) were identified between 2007 and 2011, indicating a prevalence of 6.29/100,000 (95% confidence interval [CI], 4.94-7.66) during this 5-yr period. A total of 191 incident cases of achalasia (82 men; mean age, 49.5 yr), which were not diagnosed as achalasia in the previous 4 yr, were detected in 2011, indicating an incidence of 0.39/100,000 (95% CI, 0.15-0.63) for that year. During the study period, balloon dilation therapy was performed a total of 975 times in 719 patients, and surgical esophago-cardiomyotomy was performed once per patient in 17 patients. This is the first population-based epidemiologic study of achalasia in Korea.