One hundred and fourteen women presenting during pregnancy with an abnormally high blood pressure and/or proteinuria had a renal biopsy usually on the 8th day following delivery. The pathological specimens were examined by light and/or electron and/or immunofluorescence microscopy. Forty-one cases were studied with all three techniques. The patients could be allocated to six groups on the basis of clinical criteria. The first two groups (52 patients) showed the typical clinical and pathological features of classical preeclampsia. The remaining 62 women (four groups) had isolated hypertension, and, of these, 42 had a renal pathological pattern similar to that of preeclampsia. These 42 patients also had persistent hyperuricemia. Thus in pregnancy, hypertension and persistently elevated uric acid levels are indicative of glomerular lesions of "pregnancy induced nephropathy".