The classification and the most appropriate treatment of dysplastic lesions of the larynx continue to be controversial issues. Aim of present study was to evaluate the incidence of precancerous lesions of larynx, their potential to evolve in relation to grade of dysplasia, and the most appropriate treatment. The study is based on the review of a series of 207 patients (157 (75.9%) male, 50 (24%) female) with keratosis of the laryngeal epithelium, with or without dysplasia. Patients were divided into four groups, according to Friedmann's classification (1986), based on presence and grade of any dysplasia. The follow-up period ranged from approximately 7 to 16 years. With regard to progression of the disease, 159 of the 185 patients considered were cured following initial treatment (85.9%), whereas 26 (14.1%) had recurrences. Of the latter, 19 had a single recurrence and 7 had multiple recurrences. Progression to carcinoma occurred in a total of 12 cases, above all in patients with the highest grades of dysplasia. Results emerging from this study confirm not only that dysplastic lesions of the larynx have the potential to evolve into frankly malignant lesions, but also that this capacity to evolve is significantly correlated with grade of dysplasia of the covering epithelium. Therefore, the histological classification of precancerous lesions of the larynx, based on the presence or absence of atypical cells and on their severity, is clearly valid from a clinical standpoint, representing, above all, an important prognostic factor. As far as treatment is concerned, mucosal stripping at site of the lesion is considered to be the treatment of choice for precancerous lesions of the larynx. Nevertheless, in patients presenting keratosis with a higher grade of dysplasia, it is mandatory to consider more aggressive treatment.