The aim of the study was to investigate the multi-factorial phenomenon of possible postoperative thrombocytopenia after aortic valve replacement (AVR) with the freedom SOLO (FS) bioprosthesis. A total of 254 patients underwent AVR with FS bioprosthesis in two cardiac surgery institutes. Platelet counts were measured preoperatively, immediately postoperatively and daily until the 11th day postoperatively. A multivariate generalized estimating equation model was applied to identify prognostic factors for whether or not patients postoperative platelet counts indicated no thrombocytopenia (platelet count >150 10(3)/mm(3)) versus at least mild thrombocytopenia (≤150 10(3)/mm(3)). Preoperatively, 11.2% of patients showed thrombocytopenia. The preoperative platelet count averaged 233.0 ± 83.2 10(3)/mm(3). The postoperative mean of platelet counts decreased daily reaching a minimum mean of 88.4 ± 58.8 10(3)/mm(3) 3 days after surgery and then started to increase, with the Day 11 postoperative mean of 173.3 ± 51.8 10(3)/mm(3). Compared with patients with no preoperative thrombocytopenia, patients with preoperative thrombocytopenia had an 8.69 increased odds of being in the group with postoperative platelet count <150 10(3)/mm(3). No major haemorrhagic or thromboembolic event was reported during hospitalization. This study shows that thrombocytopenia after the FS bioprosthesis replacement is a transient postoperative phenomenon, largely resolved within a few days after surgery, with no clinical consequences and haemodynamic dysfunction.