The precise moment for weaning a patient off extracorporeal membrane oxygenation (ECMO) is not always easy to establish. Also, mechanical causes may obligate to disconnect the patient from the circuit before the optimal weaning off. In these selected cases, the patient can be disconnected from the circuit and the cannula can be left in place (stand-by cannula) until the patient’s stability without ECMO is assured. The aim was to describe our experience with the stand-by cannula. Single-institution, long-term retrospective study in a pediatric tertiary care hospital. Neonatal and pediatric patients who were under ECMO and needed stand-by cannula before definitive de-cannulation were included. During 18 years, 166 children required ECMO. In 31 patients (18.7%), stand-by cannula was performed before the weaning off. Twenty patients (64.5%) were newborn. The main reason for requiring ECMO in these newborn was persistent pulmonary hypertension. Eleven patients were pediatric and their main cause for requiring ECMO was cardiogenic shock (six patients, 54.4%). The reasons for requiring stand-by cannula were the uncertainty of a successful weaning off in 17 patients (54.8%), to undergo surgery in 10 patients (32.3%) and to replace the circuit in four cases (12.9%). The median duration of stand-by cannula was 12 h (IQR 6–24). Heparinized saline serum was the main maintenance perfusion (28 patients, 90.3%). Three patients needed to restart support with ECMO. Only one mechanical complication was detected. Stand-by cannula is a safe technique, which allows performing a quick re-entrance on ECMO if the weaning off fails.