Objective To observe the RASSF1A expression in laryngeal keratosis and laryngeal squamous cell carcinoma and investigate the relationship between the gene and the occurrence and development of this disease. Methods The specimens of keratosis of larynx(43 cases)and laryngeal squamous cell carcinoma(31 cases)in Oto-laryngology-Head and Neck surgery of Anhui provincial hospital from Dec 2009 to Dec 2012 were collected.Nor-mal vocal fold mucosa from the cadaveric head as control group(8 cases)were collected.Immunohistochemical meth-ods were used to detect the expression of RASSF1A protein in these tissues.The diffuse distribution of brown gran-ules in the cell cytoplasm yielded positive results and the nucleus was not coloring.The percentage of positive cells of every section,and the average standard deviation(￣x±s)were calculated.SPSS17.0 statistical analysis software was used to analyze the data,P<0.05 for the difference was statistically significant.ResuIts The RASSF1A expes-sion in laryngeal squamous cell carcinoma,normal laryngeal mucosa,squamous cell carcinoma of the larynx and la-ryngeal keratosis were compared.The differences of RASSF1A expression were statistically significant (P<0.05). The difference of RASSF1A expression in keratosis of larynx and normal laryngeal mucosa was not significant (P>0.05).RASSF1A expression in the clinical stage from I to IV of laryngeal squamous cell carcinoma gradually de-clined.During the clinical stage,the difference had statistics significance (P<0.05 ).In high differentiated squa-mous cell carcinoma,moderately differentiated squamous and poorly differentiated squamous,the differences of RASSF1A expression were insignificant (P>0.05).ConcIusion The reduction of RASSF1A expression correlated with laryn-geal squamous cell carcinoma,which has certain significance for the different ion of carcinoma and laryngeal precan-cerous lesion.