Anisakis simplex is a nematode which can parasitize many different kinds of fish or cephalopods (codfish, salmon, tuna, mackerel, hake, etc). Anisakis simplex can cause different diseases in humans. The human being acquires the larvae by eating raw or undercooked seafood. Acute anisakiasis is probably caused by an inflammatory and/or allergic response in the digestive tract mucosa with abdominal pain. It can also induce IgE-mediated reactions with several clinical manifestations ranging from urticaria/angioedema to anaphylaxis. Chronic anisakiasis results from abscesses or eosinophilic granulomas caused by parasite invasion. This later form can mimic appendicitis, duodenal ulcer, inflammatory bowel diseases and intestinal obstruction. An early gastroduodenoscopy can confirm the diagnosis and prevent the complications. Serodiagnosis of anisakiasis is difficult since many Anisakis antigens show cross-reativity complications. In fact many people have high IgE titles in the absence of obvious allergic reactions to seafoods. As preventive measures heating for 10 min over 65 degrees C or freezing (minus 20 degrees for 24 h) destroys the infectivity of the larval stage but not always prevent allergic reactions.