Abstract: Background The Lesch-Nyhan syndrome (LNS) is a rare x-linked excessive disorder of purine metabolism, caused by the congenital absence of hypoxanthine guanine phosphoribosyl transferase (HGPRT). Case report In January 2000 a 2 year old boy was referred to a paediatric dental office in Landshut, Germany, because of severe and repeated lip chewing and aggressive tongue biting. A medical history revealed a normal pregnancy with no complications but a diagnosis of muscular hypotonia was made at four months of age. At 18 months a diagnosis of LNS was established through biochemical analysis and molecular examinations. The child displayed self-destructive behaviour, typical in children with LNS. Shortly thereafter the patient was supplied with arm cuffs for self-protection which were not tolerated and the self-mutilation continued. Eventually the extraction of all primary teeth was deemed necessary to prevent additional medical problems for this child. Follow-up One year after the dental extractions the patient presented with no bite injuries but was now using his fingers to injure himself.