It is speculated that a once-daily dosage of immunosuppression can increase adherence and thereby graft survival. Until now, there have been no studies on once-daily use of Tacrolimus extended-release formulation (TAC-ER) in children following pediatric kidney transplantation. In 11 stable pediatric kidney recipients >10 years, efficacy, safety, and tolerability of a switch to TAC-ER were observed over one year. Adherence was determined by use of the BAASIS-Scale Interview and comparison of individual variability of Tacrolimus trough levels. Over the observation period, two acute rejections were observed in one girl with nonadherence and repeated Tacrolimus trough levels of 0 ng/m. Beside this, there were no acute rejections in this trial. TAC dose was increased in 3/11 patients and decreased in 2/11 patients within the course of the study. Six patients did not require a dose adjustment. All but one patient had a maximum of 1 dose change during therapy. Mean Tacrolimus dose, trough levels, and Glomerular filtration rates were also stable. Adherence, as measured by BAASIS-Scale Interview and coefficient of variation of Tacrolimus trough levels, was good at all times. It is concluded that conversion to Tac-ER is safe in low-risk children following pediatric kidney transplantation.