['Chronic urticaria (CU) may affect up to 1% of the general population. Anisakis simplex hypersensitivity is frequent in areas where raw fish is consumed and A. simplex allergy represents a relevant cause of acute urticaria. We assessed the possible association between CU and A. simplex sensitization in an area where marinated fish is very frequently eaten.', 'A thorough history of CU was sought in 919 adults seen at the Allergy Center, Bari. CU patients and 187 controls underwent skin-prick testing with a commercial extract of A. simplex, and reactors were recommended a 6-month raw-fish-free diet regimen. Responders were followed after a further 3 months.', 'Of 919 subjects, 213 (23%) met the criteria for CU and 106/213 (49.7%) were sensitized to A. simplex with a significant difference between patients aged >65 or <65 years (56 vs. 41%, respectively; p < 0.05). All patients hypersensitive to A. simplex were regular consumers of marinated fish. In a control population without CU, the prevalence of A. simplex sensitization was 16% (p < 0.001). The 6-month diet regimen led to the disappearance of urticaria in 82/106 cases (77%) versus 1/42 (2%) subjects who did not change their dietary habits (p < 0.001). All nonresponders were sensitized to house-dust mites. Of 75 responders who were followed-up after 3 months, CU relapsed in 88% of those who had reintroduced raw fish versus 14% of those who were still on the diet (p < 0.001).'] Is anisakis simplex hypersensitivity associated with chronic urticaria in endemic areas?