Urticaria and angioedema (UA) represent a syndrome that is frequently encountered in children and adults. However, although they are often associated (in up to 50% of some patient populations), these two clinical entities should not be considered synonymous because they have distinct clinical and histopathological characteristics. The frequency of UA in drug-induced pathologies is quite high Here we report a retrospective survey of 2287 patients, observed between 1988 and 1997 presenting one or more episodes of drug-induced UA. In 1,973 patients (86.2%) [639 (32.4%) males and 1,334 (67.6%) females] a specific drug responsible for UA was identified. Particularly over the last two years the frequency of drug-induced UA has tended to increase, being more prevalent in females and the majority of cases (576: 23.1%) occuring during the third decade of life. The most frequently involved drugs are anti-inflammatory (particularly acetylsalicylic acid) and antimicrobial agents (mainly beta-lactams).