The German-Swiss-Austrian Group on Maxillofacial Tumors (DOSAK) has been performing observational studies in oral cancer. Since 1989, approximately 1600 cases of tumor of the head and neck per years has been collected in a central tumor registry. The database consists of more than 16,000 patients from 71 clinics; almost two-thirds are primary cases of squamous cell carcinoma. The data show great differences in patho-anatomical findings, therapy concepts, and five-year survival rates among the hospitals.