A 2-year-old child suffered several episodes of maculoerythematous facial exanthema and facial angioedema just after eating sole and hake. Allergologic study: skin prick test (SPT) was positive to cod, sole, hake and negative to Anisakis simplex. Specific IgE was positive to hake (1.31 kU/l), sole (2.90 kU/l) and cod (9.45 kU/l). He was recommended to follow a fish-free diet. After a fish-free diet of 3 years, his SPT became negative to hake, sole and cod, and specific IgE negative to hake, cod and sole. An open oral challenge was performed and he was able to eat hake (200 g) without any symptoms, so a normal diet was permitted. The child ate regularly fish twice a week during 8 months with good tolerance and then began suffering oral allergy syndrome with hake, sole, tuna and salmon. At this moment, SPT was positive to cod, sole, hake and tuna and specific IgE turned positive to hake (5.3 kU/l), sole (2.9 kU/l), cod (6.7 kU/l) and tuna (5.3 kU/l). Case B