Hereditary ataxias associated with cerebellar atrophy are a heterogeneous group of disorders. Selection of appropriate clinical and genetic tests for patients with cerebellar atrophy poses a diagnostic challenge. Neuroimaging is a crucial initial investigation in the diagnostic evaluation of ataxia in childhood, and the presence of cerebellar atrophy helps guide further investigations. We performed a detailed review of 300 patients with confirmed cerebellar atrophy on magnetic resonance imaging over a 10-year period. A diagnosis was established in 47% of patients: Mitochondrial disorders were most common, followed by neuronal ceroid lipofuscinosis, ataxia telangiectasia, and late-onset GM2 gangliosidosis. We review the common causes of cerebellar atrophy in childhood and propose a diagnostic approach based on correlating specific neuroimaging patterns with clinical and genetic diagnoses.