BACKGROUND: Data from the American College of Surgeons National Surgical Quality Improvement Program identified our hospital as an outlier for preoperative computed tomography (CT) use in the diagnosis of acute appendicitis in children. We performed a quality improvement project to reduce this utilization in favor of ultrasound-based diagnoses (ultrasonography [US]) through creation and implementation of an evidence-based appendicitis algorithm. METHODS: Over a 2-y period (1 y preceding and 1 y following institution of the algorithm), the clinical information of all pediatric patients operated on for suspicion of acute appendicitis following imaging studies in our institution was collated. Basic characteristics were compared before and after protocol implementation using the chi-square test for categorical variables and the nonparametric, independent sample test of medians for numerical variables. Imaging modalities used and clinical outcomes were compared using chi-square analysis. RESULTS: A total of 227 patients (117 preprotocol and 110 postprotocol implementation) were evaluated in our emergency department and operated on for suspicion of acute appendicitis. There were no differences in age, sex, race, or body mass index between the two periods. There were also no differences in length of stay (P = 0.27), acute and perforated appendicitis rates (P = 0.59), negative appendectomy rates (P = 0.40), or postoperative complications (P = 0.19). There was a significant reduction in the utilization of CT, from 65.8% to 22.0%, with a concurrent increase in the utilization of US (P < 0.001). CONCLUSIONS: With the implementation of a standardized, multidisciplinary algorithm, CT utilization was decreased and concurrently US utilization was increased without sacrificing diagnostic accuracy or patient outcomes.