Data about contact allergen sensitization (CAS) in children with atopic dermatitis (AD) are limited. The purpose of this study was to identify the frequency and patterns of CAS in children with AD by using a ready-to-use patch test system. After receiving the history of CAS in the patients, the severity of AD and IgE-mediated allergen sensitization were determined. Of 134 children with AD, 33.8%(n= 45) had at least 1 positive reaction. The most frequent positive reaction was to nickel sulfate (NS)(37.8%, 17/45), followed by methylchloroisothiazolinone (20.0%, 9/45) and thimerosal (15.6%, 7/45). The total Scoring Atopic Dermatitis (SCORAD) score was significantly higher in the NS-sensitized group (P= 0.036). The patients with NS sensitization had moderate-severe AD more frequently than those without any reaction (P= 0.020). When the SCORAD score was evaluated in detail, extent of eczema, score of sleep loss, and pruritus were significantly higher in the patients with NS sensitization than those without any reaction (P= 0.002, P= 0.001, and P= 0.002, respectively). Our study confirms the necessity of CAS in the management of AD. In particular, NS sensitization should be considered for children with severe AD or larger extent of eczema and trunk involvement.