Hemihypertrophy refers to asymmetry of the body to a greater degree than can be attributed to normal variation. Most causes can be diagnosed from history and physical examination. Hemihypertrophy is cosmetically unsightly and the psychological impact can be quite prolonged. This article reviews the causes and differential diagnosis of hemihypertrophy and offers an approach to the management of this condition. Children with isolated hemihypertrophy are at increased risk for neoplasms. Periodic abdominal ultrasound examination and physical examination during infancy and childhood are recommended for early tumour detection.