The letters of referral to the hospital with respect to 70 dental patients with medical problems relevant to dental treatment were studied for information about the medical history. The relevant medical history had been documented in fewer than 40% of the referrals. Referrals from medical practitioners more frequently contained relevant histories (57%) than did those from dental practitioners (34%). Some important problems, such as the tendency to bleed and the predisposition to infective endocarditis, were documented in most instances but other problems, such as a history of corticosteroid treatment or of respiratory disease, were often omitted. Dental practitioners should appreciate that their documentation of medical problems is not superfluous since it helps by providing another line of defense against error.