Purpose <p>We aimed to determine differences in treatment and management of forgotten ureteral stents between adult and pediatric patients.</p> Methods <p>The records of patients treated for forgotten ureteral stents were retrospectively evaluated. Reasons for stent placement, duration of stenting, stent fragmentation status, types and numbers of surgeries performed for stent removal, length of hospital stay, complications, and treatments were recorded.</p> Results <p>There were 43 (37%) patients in the pediatric group and 72 (63%) patients in the adult group. Mean age in the pediatric group was 7.65 ± 4.01 years, while it was 53.18 ± 18.29 years in the adult group. Hydronephrosis and hematuria rates were significantly higher in the adult group (40.3% vs. 20.9, <i>p</i> = 0.033; 33.3% vs. 16.3%, <i>p</i> = 0.046, respectively), whereas fever and sepsis rates were significantly higher in the pediatric patient group (39.5% vs. 12.5%, <i>p</i> = 0.001; 11.6% vs. 1.4%, <i>p</i> = 0.027, respectively). In terms of removal method, endoscopic cystolithotripsy and percutaneous nephrolithotomy (37.2%) were the methods most frequently applied in the pediatric group, and ureteroscopic lithotripsy (34.7%) was used in adults.</p> Conclusions <p>Forgotten ureteral stents can cause life-threatening complications in both pediatric and adult patients due to encrustation and stone formation. Endourological surgeries can be safely performed for treatment in both groups.</p>