A few studies have examined the specific informational needs of the population with amyotrophic lateral sclerosis. The aims of this study were to describe the information-seeking behavior and information needs of patients with amyotrophic lateral sclerosis and their families in Korea by analyzing messages from an online patient community. A total of 1047 messages from the question and answer forum of the “Lou Gehrig’s Disease Network” (http://cafe.daum.net/alsfree) from January 2010 to September 2015 were collected. The word frequency, main questions, and asker of the messages were analyzed and coded. Terms such as “hospital,” “mother,” “father,” “gastrostomy,” and “ALS” were most frequently identified. The most commonly mentioned main topic was about disease-specific information, while the most frequent subcategory was symptoms or management of symptoms. Other prominent categories concerned information about treatment, rehabilitation, and the medical system. The people who wrote the questions were mostly the son/daughter of patients with amyotrophic lateral sclerosis. Patients with amyotrophic lateral sclerosis and their family members commonly obtained information by posting their inquiries online and have a variety of questions regarding amyotrophic lateral sclerosis in this study. The findings of this study can be used as a base of information for developing educational programs and resources for patients with amyotrophic lateral sclerosis and their families.