Fifty cases of tumors of the base of the skull, facial skeleton and nasopharynx were studied by CT. The tumoral densities were measured and compared to the pterygoid muscle density which was used as reference. Results showed no relationship between tumoral density and histology, and intravenous contrast medium injection was not useful. CT, however, does offer many advantages in the diagnosis of nasopharynx tumors, (5 cases) and in the determination of the extension of facial skeleton tumors.