Th incidence and severity of posterior subcapsular cataracts were studied in 58 children with steroid-sensitive nephrotic syndrome. Eight (14%) children had cataracts. Visual acuity was normal in all but one child. There was no relationship between total dose or mean daily dose of prednisolone (corrected for body surface area) and cataract formation. Alternate-day treatment with prednisolone for an average of half the total treatment time did not prevent cataracts. These studies show there is little risk of causing permanent visual handicap in children with steroid sensitive nephrotic syndrome, provided prednisolone treatment is carefully controlled.