Objectives: The aim of this study was to investigate the efficacy of 2-dimensional (2D) shear wave elastography (SWE) in the diagnosis of acute cystitis (AC) in children. Methods: Between June 2019 and March 2020, 126 children with AC and 126 healthy participants were prospectively investigated by 2D SWE and B-mode ultrasound. Elastographic measurements were performed by drawing the contours of the posterior wall of the bladder between the ureter orifices using a free region of interest. The quantitative 2D SWE values of the patients and the healthy group were compared. Results: The mean 2D SWE values of the bladder wall were significantly higher in patients with AC compared to the healthy group (P =.001). On B-mode ultrasound imaging, the bladder wall thickness of patients with AC was higher than that in the healthy group (P =.001). On 2D SWE, when the cutoff value used was 9.25 kPa, the sensitivity, specificity, positive predictive value, and negative predictive value were 92.1%, 88.1%, 89.3%, and 92.6%, respectively, whereas when the cutoff value used was 1.72 m/s, the sensitivity, specificity, positive predictive value, and negative predictive value were 90.5%, 88.9%, 89.1%, and 90.7%. There was a statistically significant positive correlation between the 2D SWE values and wall thickness measurements (P <.001). Conclusions: Two-dimensional SWE is a noninvasive, fast, and effective imaging method to evaluate the bladder wall in children with AC.