OBJECTIVE To examine microvascular endothelial cell function in vivo in pre-eclampsia. METHODS Iontophoresis of acetylcholine (Ach), which gives rise to endothelial cell dependent vasodilatation, and of sodium nitroprusside (SNP), which elicits vasodilatation independently of functioning vascular endothelium. METHODS Södersjukhuset, Stockholm, Sweden. METHODS Ten pre-eclamptic patients, ten healthy pregnant women and ten healthy nonpregnant women were examined. METHODS The degree of vasodilatation following iontophoretic administration of Ach compared with SNP was recorded with a laser Doppler technique, the data being analysed on a personal computer. RESULTS Both Ach and SNP administration resulted in marked vasodilatation; the magnitude of the vasodilatation was similar in the three groups of women. CONCLUSIONS Following iontophoretic administration of endothelial cell dependent or independent vasodilatators, laser Doppler measurement of blood flow demonstrated no microvascular endothelial cell dysfunction in pre-eclamptic women.