Hemihypertrophy is associated with malignant visceral abdominal neoplasms in childhood. Benign nephromegaly and nephroblastomas are both known to occur with hemihypertrophy; however, association with renal dysplasia has not previously reported. We describe an infant presenting with recurrent haematuria who had segmental hemihypertrophy, ipsilateral renal dysplasia and contralateral benign nephromegaly. Although debated, renal dysplasia may predispose to and predate malignant change. Rational management and optimal surveillance of renal dysplasia and benign nephromegaly in hemihypertrophy is discussed.