Halothane has been shown to inhibit platelet aggregation and may, therefore, prevent intraoperative platelet activation. The aim of this study was to compare the effects of volatile anaesthetics on platelet activation, including the transformation into an adhesive platelet phenotype. After in vitro exposure to volatile anaesthetics, the expression of the adhesion molecule P-selectin and the internalization of the receptor for the von Willebrand factor (GPIb) were analysed by flow cytometry. In contrast to desflurane or N2O, sevoflurane (≥0.5 MAC, P< 0.05), halothane (≥1.0 MAC, P< 0.01) and isoflurane (≥2.0 MAC, P< 0.01) induced a significantly higher expression of P-selectin on the surface of platelets, indicating the degranulation of α-granules. In the presence of desflurane (≥0.5 MAC, P< 0.05), halothane (≥1.0 MAC, P< 0.01), isoflurane and sevoflurane (both ≥2.0 MAC, P< 0.01), a redistribution of GPIb occurred, indicating platelet activation. N2O had no effect. In conclusion, several of the volatile anaesthetics tested in vitro induced changes in the expression of P-selectin and GPIb, being characteristic of platelet activation. None of the anaesthetics investigated interfered with the platelet response to ADP stimulation.