The determination of serum lipid sialic acid (LSA) in subjects with laryngeal and oral cavity carcinomas demonstrated an important correlation between the presence of carcinoma and tumor marker elevation. 90% of positivity has been found in 60 cases of laryngeal carcinoma; 100%, on the contrary in 19 cases of oral cavity. The authors affirm the importance of LSA as a tumor marker, in particularly in monitoring patients submitted to surgical excision.