['Operator training is a key factor for the safety of carotid stenting (CAS). Whether institutional practice is associated with improved individual operator outcomes is debated.', 'To evaluate the effect of the institutional experience on outcomes of new trainees with CAS, a retrospective analysis of a prospectively held database was performed.', 'The overall study period, 2004-2012, was divided into two sequential time frames: 2004-April 2006 (leaders-team phase) and May 2006-2012 (expanded team phase). In the first frame, a single leader-operators team that first approached CAS and passed the original institutional learning curve, performed all the procedures; in the following expanded-team phase, five new trainees joined. Institutional CAS training for new trainees was based on a team-working approach including selection of patients, devices and techniques and collegial meetings with critical review and discussion of all procedural steps and imaging.', 'A total of 431 CAS procedures were performed in the leaders-team phase and 1026 in the sequential expanded-team phase. Periprocedural complication rates in the two time frames were similar: stroke/death (3.0% vs. 2.1%; P = 0.35), stroke (2.8% vs. 2.1%; P = 0.45) major stroke (0.9% vs. 0.6%, P = 0.49), death (0.2% vs. 0%; P = 0.29) during the leaders-team and expanded-team phase, respectively. However, rates of CAS failure requiring surgical conversions (3.7% vs. 0.8%; P < 0.0001) and mean contrast use (91.6 vs. 71.1 ml; P = 0.0001) decreased in the expanded phase. In the expanded-team frame (May 2006-2012), there was no mortality, and stroke rates were comparable between the leader and new operator teams: 2.6% vs. 1.2%; P = 0.17.'] Is safety of carotid stenting ( CAS ) based on institutional training more than individual experience in large-volume centres?