Background: In 1980 Hanifin and Rajka published major and minor criteria for atopic dermatitis (AD). Despite the early age at onset of AD, there are few prospective studies in young children of the prevalence of signs and symptoms meeting the minor criteria. Objective: Our purpose was to identify those of Hanifin's and Rajka's minor criteria that are most frequent in 2-year-old children with AD and in controls. Methods: Consecutive patients with AD (n = 221), 24 months of age or younger, were followed up to 2 years, when they were re-examined. The minor criteria were divided into 33 subcriteria, 29 of which were examined. Controls (n = 99), matched for age and sex, with no history of eczema at 2 years of age were examined in the same way. Results: At the 2-year examination 157 of 221 had ongoing AD. Seven minor criteria were met in more than one fourth of these children, namely xerosis (100%), course influenced by environmental factors (87%), facial erythema (54%), skin reactions provoked by ingested food (39%), itch when sweating (34%), positive skin prick test (29%), and hand eczema (28%). In the control group, only xerosis (40%), facial erythema (25%), and skin reactions provoked by ingested food (9%) were present in 4% or more. Conclusion: Approximately half of the 29 criteria investigated were met in 3% or fewer of the cases, indicating that they may not be of much help to the clinician. Of the minor criteria of Hanifin and Rajka, only xerosis, course influenced by environmental factors, and facial erythema were seen in a majority of patients and would therefore be useful in the diagnosis of AD. (J Am Acad Dermatol 2000;43:785-92.)