Mean platelet volume (MPV) and platelet distribution width (PDW) can help diagnose cardiovascular pathologies. In this study, we aimed to demonstrate the changes in platelet (PLT) indices in children diagnosed with bicuspid aortic valve (BAV) with mild stenosis and without stenosis to compare patients with mild stenosis with those without stenosis. A total of 73 children diagnosed with BAV (30 patients with mild stenosis and 43 without stenosis) with a mean age 9.73 ± 5.01 years and a control group were included in the study. Mean MPV value was significantly lower in the control group compared with patients with BAV with mild stenosis and patients without stenosis (p = 0.001, and p < 0.01, respectively). MPV was significantly greater in patients with mild stenosis than in patients without stenosis (p = 0.049 and p < 0.05, respectively). Patients with mild stenosis had a significantly greater mean PDW value compared with patients without stenosis and the control group (p = 0.024 and p < 0.05, respectively). There was no significant difference between patients without stenosis and the control group with respect to mean PDW value (p > 0.05). In conclusion, the results of this study demonsrate that children with BAV either with or without stenosis have increased MPV; the ones with mild stenosis have even greater values than the ones without stenosis. It emphasizes the risk of thrombosis in children with BAV.