Platelet count reduction is a common but not fully understood phenomenon after aortic valve replacement (AVR) with bioprosthesis implantation. The aim of the present study was to investigate the occurrence and the clinical impact of platelet count reduction in patients receiving the Perceval bioprosthesis compared to those receiving standard sutured stented bioprosthetic aortic valve in a randomized, controlled AVR study. PERceval Sutureless Implant versus STandard Aortic Valve Replacement is a prospective, randomized, adaptive, open-label trial. Patients were randomized (March 2016-September 2018) to AVR with a sutureless or stented valve. Ad hoc analyses have been performed to evaluate the occurrence of platelet count reduction and the clinical impact of the platelet variations in the 2 groups. The Perceval group showed a higher platelet reduction than the control group (46% vs 32%). The phenomenon was transient in both groups, with a slow recovery of the platelet count by hospital discharge. No differences were observed between groups regarding need of transfusions, blood loss, major bleeding and stroke events. The Perceval sutureless aortic bioprosthesis implantation is associated with higher rate of transient platelet reduction as compared to stented bioprostheses for AVR. However, the platelet count reduction is transient and the decline does not affect the patient's clinical outcomes. Current explanations for this phenomenon are speculative, and further investigations are required to elucidate it. NCT02673697-ClinicalTrials.gov-4 February 2016.