Although renal disease in pregnancy is uncommon, it poses considerable risk to maternal and fetal health. This article discusses renal physiology and assessment of renal function in pregnancy and the effect of pregnancy on renal disease in patients with diabetes, lupus, chronic glomerulonephritis, polycystic kidney disease, and chronic pyelonephritis. Renal diseases occasionally present for the first time in pregnancy, and diagnoses of glomerulonephritis, acute tubular necrosis, hemolytic uremic syndrome, and acute fatty liver of pregnancy are described. Finally, therapy of end-stage renal disease in pregnancy, dialysis, and renal transplantation are reviewed.