Allergy to mollusk has rarely been described. The limpet, belonging to Phylum mollusca, is one of the most frequent mollusks in the Canary Islands, as in all warm maritime regions. We report two cases of atopic patients who developed anaphylactic reactions after ingestion of this mollusk. Type I hypersensitivity to limpet antigens was demonstrated by means of immediate skin test reactivity, specific IgE determination by RAST, and histamine release test to cooked limpet extract. The controls did not react to any of these tests. Allergic activity was only found with a cooked limpet extract; this suggests that the offending antigen/s may have been released by cooking this food.