This study focuses on the detection of medically compromised dental patients in the Netherlands by means of a validated patient-administered medical risk-related history (MRRH). Due to social changes and scientific innovations in the past decade, more medically compromised patients will be needing special dental treatment. The medical problems of 29,424 dental patients (age 18 years and over) from 50 dental practices in the Netherlands were registered by means of the MRRH. The patients were classified according to the ASA risk-score system, which was modified for dental treatment. An inventory of the number and nature of medical problems and the modified ASA risk score was drawn up in relation to dental treatment and age. The average age of the patients was 37.1 +/- 13.5 years. According to the current guidelines, dental treatment must be modified if the patient has an ASA score of III or IV. A relatively high percentage of patients ages 65-74 (23.9%) and 75 or over (34.9%) did have an ASA score of III or IV. Furthermore, the medical problems were classified into 10 categories, and the relationship to age was examined. The conditions that increased with age were hypertension and cardiovascular, neurological, endocrinological, infectious, and blood diseases. For the dental practice, these results mean that the MRRH can play an important role in adapting dental treatment to the specific needs of patients. This is especially important in the case of elderly patients.