To investigate the role of p53 nuclear protein mutations in the initiation and progression of laryngeal carcinoma, 111 premalignant and malignant laryngeal lesions (19 specimens with hyperkeratosis and 92 with carcinoma) were studied immunohistochemically. Over-expression of p53 was observed in 8 cases (42%) of laryngeal hyperkeratosis and 44 cases (47%) of laryngeal carcinoma. However, the expression of p53 showed no relationship to patients' clinical courses. Our study confirms that p53 overexpression can be found in laryngeal carcinogenesis and is an early event but not a useful prognostic marker.