SummaryLesch‐Nyhan syndrome is an X‐linked disease caused by the deficiency of hypoxanthine phosphoribosyltransferase, an enzyme involved in the purine salvage pathways. It is characterized by severe gout, choreoathetosis, self‐mutilatory behaviour and mental retardation. The derivation of mice genetically deficient in this enzyme may help to elucidate the pathogenesis of the neurological abnormality where previously models using drug administration to mimic the disorder have had to suffice.