Adolescent and adult clinics for patients with inborn metabolic errors are needed first to provide care to patients who develop distinctive problems as their different disorders impinge on education, career and family life. The selection of patients in this article illustrates the range of the problems. Fundamental research will be a shared interest with paediatricians and others, but outcomes of care and treatment in young adults and in patients in middle life must be a special concern of adult clinics. It is essential to gather that information. The best model is probably an outpatient service for all ages in a single centre with paediatricians and adult physicians contributing and sharing access to dietary and laboratory services. Such a model would be best for generating the meetings, case discussions and initiatives that contribute to a thriving and energetic unit. Clearly identified centres in each country would be an effective means of acquiring the information on the adult follow-up of these uncommon disorders.