From 1954 to 2001 the author Shimizu, M. worked for oral tumor and cancer researches in clinical and basic fields at Tokyo Medical & Dental University till 1981, afterwards at Oita Medical University till 1996, now at the Hospital in Saiki. At first he studied the clinical research under three Professors, Adachi at Dept. of Radiology, Nakamura and Ueno at Dept. of Oral Surgery. On the article, Shimizu wrote his severe clinical experiences during 15 years at first where he was taught by his teachers. The treating possibility for oral cancer was strictly limitted at that time, but it was changed by passing of the historical years. Therefore, he encountered some unusual and sad cases, which would be not believable from the present situation. For example, the age limitaion for tumor operation like as mandiblectomy of the lower gum cancer was set under 60 years old. The first trial of the general anesthesia failed in an operation for a female patient with cancer of the mouth floor, because of a total lack of preparation. In 1954 otherwise, he could observe the first lucky male case with cancer of the maxillary sinus, which was firstly decided as inoperable but secondary cured by radiotherapy alone radically over 14 years. The article ended at the year of 1970, where he was a still young trainee for oral surgerv. If a chance for the next article were given to him, he could report the chronicle till 2001.