Thirty-six patients (24 with oral cavity or oropharynx cancers and 12 larynx cancers) were prospectively examined with computed tomography (CT) to determine its value in staging the primary tumor and to compare with the clinical staging. The CT staging agreed with the clinical staging in 50% (12/24) of the oral cavity or oroharynx cancers and in 67% (8/12) of the larynx cancers. The CT upgraded the clinical staging in 29% (7/24) of the oral cavity or oropharynx tumors and in 33% (4/12) of the larynx cancers, whereas the CT downgraded the clinical staging in 21% (5/24) of the oral cavity or oropharynx cancers. There is no downgrade on CT in larynx cancer. The post-surgical confirmation was not made in most of the cases. The possible causes of disagreement between the CT and the clinical staging, and the diagnostic value of the CT in evaluation of the primary tumor in oral cavity, oropharynx and larynx were discussed.