Renal biopsies from hypertensive pregnant women performed 8 to 10 days postpartum were processed by morphometric analysis. We allocated the 74 patients into four groups according to the respective forms of pregnancy hypertension, i.e. preeclampsia and gestational hypertension. Groups I and II included preeclamptic women, with (group I) or without (group II) de novo FSGS. Groups III and IV included biopsies of women with isolated gestational hypertension, appeared during the third trimester (group III) or earlier (group IV). The control group included 17 biopsies from age-matched nonpregnant women presenting with isolated hematuria. Glomerular lesions of typical preeclampsia were seen in all the biopsies of groups I and II, and in some of women with gestational hypertension of groups III and IV. Our morphometric analysis of these renal biopsies showed a progressive increase in glomerular size from early gestational hypertension, gestational hypertension of the 3rd trimester, isolated preeclampsia, and finally preeclamptic nephropathy associated with FSGS. The largest glomeruli were seen in preeclamptic women with severe hypertension and histologic lesions of preeclampsia with FSGS. Thus, both systemic hypertension and glomerular hypertrophy seem necessary to induce FSGS in this type of pathology.