For the majority of families affected by one of the neuronal ceroid lipofuscinoses (NCLs), a biochemical and/or genetic diagnosis can be achieved. In an individual case this information not only increases understanding of the condition but also may influence treatment choices and options. The presenting clinical features prompt initial investigation and also guide clinical care. The clinical labels "infantile NCL", "late infantile NCL" and "juvenile NCL", therefore remain useful in practice. In unusual or atypical cases ultra-structural analysis of white blood cells or other tissue samples enables planning and prioritisation of biochemical and genetic tests. This review describes current methods available to achieve clinical, pathological, biochemical and genetic diagnosis in children presenting with symptoms suggestive of one of the NCLs.