Although not scientifically proven, dental foci are believed to result in severe local or systemic disease. Eradicating dental foci in order to prevent possible interference with a medical treatment may be important in specific patient groups. To gain insight in the number of dental focus examinations, the medical evidence, the number of potential foci determined, as well as the treatment eradicating the focus, all dental focus examinations in 16 Dutch hospitals were registered during 3 months. A total number of 470 examinations were performed. Scheduled heart(valve)surgery and radiotherapy of the head and neck were the main reasons for a dental focus examination. Dental foci were found and treated in more than 50% of the patients examined. There was a significant difference between dentate and edentulous patients in the percentage of patients diagnosed and treated for a dental focus. More than 80% of dentate and less than 20% of edentulous patients were treated.