Platelet activation status (PAS) is used for characterizing quality and function of platelets in various experimental and clinical settings. In this study, we created a set of platelet populations differing in PAS, using stimulation of platelets with thrombin in a wide range of concentrations, and analyzed a number of how cytometric parameters, which characterize PAS by measuring P-selectin (CD62) expression. We found that PAS of a platelet population depends significantly on the specific parameters used for detecting CD62 expression and can differ several fold. We revealed the parameters which are more sensitive for distinguishing the differences between populations with similar low and similar high PAS. Selection of valid and sensitive flow cytometric parameters for PAS evaluation and distinguishing the differences between platelet populations with similar PAS can serve for diagnosis of platelet-associated disorders and monitoring their course and therapeutic interventions.