Dasatinib efficiently blocks platelet aggregation induced by direct FcγRIIa clustering or by sera from HIT patients. Platelets from healthy donors were treated or not with increasing concentrations of dasatinib and stimulated by FcγRIIA clustering by incubation of platelets with (A) 2 μg/mL of monoclonal antibody IV.3 for 1 minute followed by addition of 30 μg/mL goat anti–mouse F(ab′)2 or with (B) HIT sera and heparin (0.5 IU). Platelet aggregation was assessed using a Chrono-log dual-channel aggregometer under stirring at 900g. The aggregation profiles shown are representative of 3 or 4 independent experiments.