The UICC and AJCC never classified ethmoid malignancies prior to the latest edition (1997). Most classifications in the literature refer to a single histological type (estensioneuroblastoma or carcinoma) while others basically consider the intracranial extension, without distinguishing between intra or extradural. Still others consider invasion of the orbit. There is as yet no classification which considers all the prognostic factors associated with the extension of this neoplasm. The authors reviewed 84 patients with ethmoid malignancy who had undergone anterior cranio-facial resection between 1987 and 1994 and had been followed up for a minimum of 36 months. Of these patients, 43 were recurrences of previous treatment while 42 had not previously been treated. The breakdown was as follows: 45 adenocarcinoma, 14 squamous cell carcinoma (more or less differentiated), 8 etesioneuroblastoma, 6 adenoidocistic carcinoma, 5 melanoma and 6 rare forms. These cases were staged according to a new classification identifying the worst prognostic factors: invasion into the dura and, above all, intradural extension; invasion of the sphenoid sinus, orbit, and in particular the orbit apex, the frontal sinus, the maxillary sinus, the pterygoid, infratemporal fossa and the skin. Until 1994 we used this classification which is similar to the one proposed by the UICC in 1997. On the basis of this classification our case breakdown is as follows: T2 35, T3 24, T4 25 (there were no cases of T1). Since a patient can live as much as 4-5 years with a recurrence but the recurrences all appeared within 2 years after surgery, we used a NED survival at 36 months as index of healing. The NED survival at 36 months was: T2 54%, T3 41%, T4 8%. In patients which had not received prior treatment the NED survival was: T2 63%, T3 45%, T4 9%. The progressive worsening of prognosis from T2 to T4, particularly in patients which had not been pretreated, leads us to assume that the true prognostic factors for malignant ethmoid tumors have been identified.