Background. Using pediatric donors for single-kidney transplantation (SKT) can increase the number of possible recipients. However, it is unclear when SKT involving small pediatric donors and adult recipients can safely be performed without compromising graft outcome. Methods. From 2013 to 2017, a total of 102 SKTs in adult recipients were performed in our center using pediatric donors aged <12 years. We compared the outcomes from donors aged 8 to 36 months (the small-kidney group [SKG], n = 46) and from donors aged 3 to 12 years (the big-kidney group [BKG], n = 56). The median follow-up time was 30 months in the SKG and 28 months in the BKG. Results. All patients achieved satisfactory renal function after transplantation, despite the fact that some patients (SKG, 19.6%; BKG, 28.6%) developed delayed graft function. One-year graft survival and death-censored graft survival in the SKG were 89.1% and 100%, respectively, comparable to the results in the BKG (92.9% and 98.2%). One year later, the graft and patient survival rates in both groups remained unchanged. Pulmonary infection was the main cause of death in patients with a functioning graft (SKG, 4 patients; BKG, 2 patients). Proteinuria occurred early in some patients (SKG, 30.4%; BKG, 19.6%) and decreased gradually within the first year posttransplantation. Conclusions. SKT from pediatric donors aged 8 to 36 months to selected adult recipients produced excellent intermediate-term outcomes, comparable with those when older pediatric donors were used. This study provides evidence to support a lower age limit for SKT from pediatric donors.