White matter changes are seen in a spectrum of disorders in children and adolescents. Understanding their distribution and appearance helps to reach diagnoses in daily radiologic practice. This pictorial essay will outline the magnetic resonance imaging (MRI) appearances of diseases with white matter changes including demyelinating diseases, dysmyelinating disorders/leukodystrophies, infections, autoimmune diseases, vascular causes, mitochondrial disorders and neurocutaneous syndromes, along with a brief overview of clinical aspects of the diseases such as typical age of presentation, etiology, symptoms and signs and treatment options. This article highlights important features in common white matter diseases in children and adolescents.