Changes in mean arterial pressure (MAP) and plasma catecholamine concentrations in response to endotracheal intubation were examined in 8 patients who had received d-tubocurarine and 10 who had received suxamethonium. MAP fell after induction of anaesthesia and administration of the relaxant by a mean of 11 mmHg in those who had received suxamethonium and 19 mmHg in those who had received d-tubocurarine (p less than 0.05 for each). MAP rose sharply when the trachea was intubated, by a mean of 29 mmHg for the suxamethonium group, and 35 mmHg for the curare group (p less than 0.001 for each). A significant rise in plasma noradrenaline was also noted after intubation in each group, 51% (p less than 0.01) for the suxamethonium group and 28% (p less than 0.05) for the d-tubocurarine. The results suggest that the fall in MAP after administration of d-tubocurarine does not attenuate the pressor response associated with intubation.