Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.Objectives: Ultrasonography in a child with suspected appendicitis is primarily performed to detect inflamed appendix, whereas secondary findings are important in patients with a nonvisualized appendix. The aim of this study is to evaluate the gallbladder wall thickness and volume in patients with suspected appendicitis and search an association between these parameters and appendicitis. Methods: Between January 2018 and August 2018, 113 patients with suspected appendicitis were included in this prospective study. Gallbladder and right lower quadrant were evaluated in separate sessions by different radiologists. The wall thickness along with the width, length, and height of the gallbladder was measured and recorded for each patient. Assessment of the appendix was classified as acute appendicitis, normal, and equivocal. Statistically significant association was sought between the thickness of the gallbladder wall and diagnosis of appendicitis. Results: Gallbladder wall thickness was significantly higher in patients without appendicitis (P = 0.017), whereas significantly increased gallbladder volume was observed in patients with appendicitis (P = 0.004). Receiver operating characteristic analysis showed gallbladder wall thickness threshold of 0.5 mm with a sensitivity of 83.3, specificity of 93.9, and volume threshold of 41.6 mL with a sensitivity of 100 and a specificity of 0.69. Conclusions: Gallbladder wall thickness and volume measurements were associated with the diagnosis of appendicitis in pediatric patients.