A retrospective study was carried out in 40 infants, age 1 to 24 months, with urticaria. Acute urticaria was seen most frequently (85%), followed by recurrent (10%) and chronic disease (5%). Several clinical features such as frequency of angioedema and hemorrhagic lesions appeared to be specific to urticaria in infants. An underlying cause was identified or suspected in 65% of cases: foods in 25%, and drugs and infections in 37.5%. Under 6 months of age, all infants had acute urticaria and 75% had cow's milk allergy. After 6 months of age, the main causes were drug intake (mostly aspirin and amoxicillin) and/or infections (mainly viral) (50%). Atopy was not overrepresented (20%), although a possible link between atopy and recurrent urticaria was noted. After a follow-up of 2 to 7.5 years, 96% of patients were symptom free. Thus, our results indicate that clinical and etiologic features of urticaria in infants are somewhat different from those of adults and children.