Geographical differences in the incidence of amyotrophic lateral sclerosis (ALS) have been reported, and there are still many unresolved problems. The incidence as well as epidemiologic data of ALS is not known in Korea. Web-based multicenter registry of ALS, the Korean ALS registry, was established at January, 2011. The aim of "the Korean ALS registry" is the following: (1) to establish a database for the prospective collection of epidemiological information; (2) to assess the incidence and prevalence; (3) to find the temporal and geographic trends in the disease; (4) to define the full clinical spectrum of the disease; (5) to develop treatment guideline based on the database.