The goal of this study was to determine subsequent malignancy on a discrete group of precancerous laryngeal lesions, and to assess the mortality. In a series of 227 patients, average age 51.8 years (ranging from 13 to 80 years). The changes were followed-up for 12.3 years (minimum of 5 years and maximum of 40 years). 58% are living without any sign of premalignant laryngeal mucosal disease, 13% with controlled precancer, and 3% in remission after surgery for carcinoma. 11% died (9% due to cause unrelated to the cancer) and 15% were lost for follow-up. 17% of the group with mucosal hyper- or metaplasia progressed to mild dysplasia, but none progressed to carcinoma. Reinke's oedema recurred in 4%, no malignancy was observed. Carcinoma developed in 16% of laryngeal papilloma (8% in situ and 8% invasive). 15% of mild dysplasia progressed in severity, but none transformed to malignancy. Moderate dysplasia progressed to severe dysplasia in 12%, carcinoma in situ in 4%. Of cases with severe dysplasia 13% developed in situ carcinoma while 43% progressed to invasive cancer. In the whole series progression to severe grade was seen in 7.1%, and malignant transformation in 4.4%. Three patients (1.3%) died due to subsequent carcinoma. Our results agree with some authors; but the majority of them reports higher incidence of malignant transformation. Invasive carcinoma was diagnosed in the follow-up in seven patients. Those represent only 3% of all laryngeal carcinomas diagnosed in our department in the same period of time. Based on the data we have evaluated the intensity of follow-up in patients with hyperplasia, metaplasia, keratosis and mild dysplasia.