Anisakidosis, human infection with nematodes of the family Anisakidae, is caused most commonly by Anisakis simplex and Pseudoterranova decipiens. Acquired by the consumption of raw or undercooked marine fish or squid, anisakidosis occurs where such dietary customs are practiced, including Japan, coastal regions of Europe, and the United States. Severe epigastric pain, resulting from larval invasion of the gastric mucosa, characterizes gastric anisakidosis; other syndromes are intestinal and ectopic. Allergic anisakidosis is a frequent cause of foodborne allergies in areas with heavy fish consumption or occupational exposure. Diagnosis and treatment of gastric disease is usually made by a compatible dietary history and visualization and removal of the larva(e) on endoscopy; serologic testing for anti-A. simplex immunoglobulin E can aid in the diagnosis of intestinal, ectopic and allergic disease. Intestinal and/or ectopic cases may require surgical removal; albendazole has been used occasionally. Preventive measures include adequately freezing or cooking fish.