BACKGROUND: Accurate information on natural history and prognosis of Amyotrophic Lateral Sclerosis (ALS) is useful for patients, their families, and clinicians. This study was designed to determine natural history and prognosis in Korean ALS patients. METHODS: We surveyed 311 ALS patients who registered in Korean ALS association, on clinical and epidemiological characteristics association with demographic factors, initial symptoms, time delay of diagnosis, caregivers' burden. RESULTS: Ratio of gender was 1.6:1.0 (M:F) and the mean age onset was 50.2 years. Limb onset type was two times more frequent than bulbar onset type. Mean time delay from onset to diagnosis was 14.7 months, and neurologist did most of the diagnosis (90.4%). Multiple linear regression analyses of patient and caregiver variables on caregiver burden and care stress were significantly and independently associated with declined physical function, pain, ventilator application and short disease duration of patients. CONCLUSIONS: Present preliminary results on clinical characteristics and caregivers' burden of Korean ALS patients would be used as the basic data for the large scale of epidemiologic study on Korean ALS.