35 cases of continuous series of 841 laryngeal cancers were studied separately. Those patients had already been suffering from hoarseness for more than 2 years, in the average for 9 years. Many of these patients had been examined and treated by inhalations, and biopsies were taken because of a chronic laryngitis. Clinically in half of the cases a big carcinoma could be found. In 10 cases a chronic laryngitis had been diagnosed; in spite of the preceeding examination by microlaryngoscopy in 4 cases, however, the carcinoma could only be proved by histologic examination. The histologic examinations of the specimens regularly displayed an extended field of epidermisation of the laryngeal mucosa following chronic laryngitis, In these fields of epidermisation the carcinoma developed multicentrically and--in the early stages--mostly showed a covering-like, minutely infiltrating growth. Disseminated dot-like cancer-focuses in the epidermisation field and cancer buds arising from the basal layers of an intact covering of the hypertrophic epithelium could be observed several times. Chronic-hypertrophic laryngitis seems to favour the development of cancer within some patients (promoting factor), it even might accelerate it. As in about 6% of all the vocal cord cancers a preexistent chronic laryngitis is proved by history and clinical findings each patient with a chronic hypertrophic laryngitis must be examined by microlaryngoscopy as well as histological examinations and must be constantly observed.