Background: This study aimed to describe the clinical and imaging findings, including ultrasonography (US) findings, and long-term follow-up results in pediatric patients with localized cystic disease of the kidney (LCDK).Methods: From January 2002 to August 2020, pediatric patients diagnosed with LCDK based on imaging findings showing multiple localized renal cysts with intervening normal renal parenchyma were retrospectively reviewed. Clinical presentations and US features of the affected and contralateral kidneys were reviewed and compared with computed tomography or magnetic resonance imaging findings, if available. Results: A total of 18 patients (male:female = 11:7; median age, 8 years) were included. Initial clinical presentations were incidental findings (n = 5), abdominal pain (n = 5), or hematuria (n = 5). Of the seven (7/18, 39%) patients who showed multiple hyperechoic foci with ring-down artifacts within the cystic lesions on US, six patients showed focal calcification of the cysts on CT. Two (2/18, 11%) patients had tiny cysts in the contralateral kidney. During follow-up (range, 2–122 months), there was an increase in lesion size, with ipsilateral renal growth in four (4/18, 22%) patients. There was no renal function impairment at the initial presentation or during follow-up in all patients.Conclusions: LCDK can present with tiny calcifications (39%), contralateral tiny renal cysts (11%), and mild size increase during renal growth (22%) in children without renal function impairment. Follow-up US is recommended without surgical intervention in these typical cases.