Compared with normotensive pregnant women (n = 13), patients with severe pre-eclampsia (n = 13) had increased arterial plasma adrenaline (P < 0.001), peripheral venous adrenaline (P < 0.01), arterio-venous differences of adrenaline (P < 0.001) and venous concentration of the platelet release product beta-thromboglobulin (P < 0.001). In the pre-eclamptic group, arterial adrenaline correlated with mean blood pressure (r = 0.90, P < 0.001), heart rate (r = 0.78, P < 0.01) and beta-thromboglobulin (r = 0.82, P < 0.001), while in the normotensives adrenaline correlated only with beta-thromboglobulin (r = 0.76, P < 0.01). According to these results, sympathetic adrenal tone is increased in pre-eclampsia and may play a role in the pathogenesis of high blood pressure and platelet activation in this disease.