Micronuclei can be found in upper-respiratory epithelial cells and are related to the DNA damage caused by carcinogen exposure. Willing to verify a correlation between micronuclei frequency, smoking habit and histological dyagnosis, laryngeal mucosa biopsies were performed on Is patients affected by precancerous or cancerous lesions. The mucosal brushing, carried on the lesions with cell-scaper, was immediately fixed with alcool on microscope slide and stained with Feulgen's method. An inclination for increasing of micronuclei count in heavy smokers, even if not meaningful, was found out. An increasing of the average micronuclei count was observed through the keratosis, the dysplasia and the carcinomas. The study suggests that increased micronuclei number could be used as reliable index of neoplastic transformation.