This survey comprised thirty-four patients who were suffering from malignant tumors of the oral cavity diagnosed in a 12-year period in the Department of Oral Surgery, Royal Dental College, Aarhus, Denmark. The categories of tumors were as follows: carcinomas (twenty-seven), osteosarcomas (four), reticulum-cell sarcomas (two), and lymphosarcomas (one). Special emphasis is placed upon the calculation of two time factors, i.e., the time that elapsed from when the symptoms were first noticed until the patient consulted a physician or dentist, and the period during which the patient was under professional care up to the time at which a final diagnosis was made. The first of these periods was found to be, on an average, 4.9 months; the second period averaged 5.6 months. The most common complaints were swelling and pain, two symptoms with which the physician or surgeon often are confronted. This may be a possible reason for a relatively late diagnosis in the case of several malignant tumors. A frequently very suspect symptom, such as a persistent ulceration, was found in only thirteen of twenty-seven cases of carcinoma, whereas another symptom in the same category, disturbances in sensibility, was noted in only three cases. Because of the short observation period in some cases, no correlation between the two time factors and the prognosis was attempted. Despite the inadequacy, it may be concluded that the period of 5.6 months which in this material was found to elapse between the first consultation and the actual time of diagnosis was far too long. All lesions that do not respond to adequate therapy in 14 days should be suspected of being malignant, and the patient should be referred to a specialist for proper diagnosis.