Objective: The authors compared the prevalence of positive patch tests in atopic pediatric patients versus nonatopic controls and sought to determine if statistically significant allergen prevalence differences existed between the two groups. Design: Retrospective chart review. Setting: Rady Children's Hospital, San Diego, California. Participants: Patients with suspected allergic contact dermatitis between the ages of 6 and 18 years who had been enrolled in the Pediatric Research Equity Act Thin-layer Rapid Use Epicutaneous Test trial. Measurements: Statistical analysis used Z-scores to compare associations between positive reactions in atopic versus nonatopic patients and the prevalence of individual chemicals in either group. Results: Results showed that at least one allergen reaction was noted in 78 percent (n=79) of the patients, 89 percent (n=48) in atopic patients, and 66 percent (n= 31) in the nonatopic patients (Z-score 2.78). Eczema area and severity index scores ranged from 0 to 41.75. Eczema area and severity index scores greater than 10 correlated with a higher probability of more than three positive patch tests (Z-score [-]3.28). Statistically significant differences were also observed between atopic and nonatopic patients in regards to contact allergens, with 20 percent (n=11) of atopic patients exhibiting positive patch tests to Myroxylon pereirae and 19 percent (n=10) of those with atopic dermatitis having reactions to fragrance mix. Conclusion: The authors concur with prior studies that performing systematic patch testing is indicated in children with moderate-to-severe atopic dermatitis, given the high rate of contact allergy in the atopic group, especially those with eczema area and severity index scores greater than 10. Furthermore, prevention through exposure avoidance to the most frequent contact allergens, especially fragrances in patients with atopic dermatitis, is recommended.