The pressor response to tracheal intubation is known to be exaggerated in patients with gestational proteinuric hypertension (GPH). We have studied the effect of pretreatment with magnesium sulphate 40 mg kg-1 or 30 mg kg-1 with alfentanil 7.5 micrograms kg-1 on this pressor response in 38 patients with moderate to severe GPH. The magnesium-alfentanil combination produced better control of arterial pressure and heart rate than magnesium alone, although both techniques provided good cardiovascular control. There was no significant difference in fetal outcome between groups. Both pretreatment methods produced satisfactory control of catecholamine release.