Idiopathic Chronic Urticaria (ICU), the most common form (70-80%) of chronic urticaria is supposed to have immune basis causes. It is speculated that the promoter polymorphism of TGF-Beta1 gene may be involved in ICU. This condition is thought to affect at least 0.1% of the population and often can be severe and difficult to treat. A total of 40 patients with ICU and 41 normal subjects were studied. DNA was extracted from whole blood and TGF-Beta1 promoter -509C>T polymorphism was determined by PCR-RFLP method. Out of the 40 patients with ICU, 11 (27.5%) had CC, 26 (65%) had CT and 3 (7.5%) had TT genotypes. A higher proportion of case subjects with the C allele (CT type or CC type) was found compared with the T allele. These results do suggest an influence of genetic variability at the promoter of TGF-Beta1 gene (-509C>T) on the occurrence of ICU. This polymorphism has been shown as a useful genetic change in our study. Further work is required to confirm this result.