Basaloid squamous cell carcinoma (BSCC) is a recently described bimorphic variant of squamous cell carcinoma with distinct morphological and biological features. We describe the clinicopathological findings, along with immunohistochemical and ultrastructural investigations, in 15 new cases of BSCC of the larynx or hypopharynx observed and treated at the otolaryngology department of the University of Padua between 1989 and 1995. The world literature is also reviewed in order to develop a more accurate clinicopathological profile of the tumor. Patient records and histologic slides were reviewed in all of our 15 cases. The patient group consisted of 13 men (86.67%) and 2 women with a mean age of 63.33 years (median 69 years; range 44 to 84 years). Nine patients presented with cervical lymph node metastases. Surgical treatment was the therapy of choice; radiotherapy and chemotherapy have been applied in different combinations. Follow-up was available on all 15 cases. Local recurrence was described in 3 cases. Five of the 9 patients with cervical lymph node metastases developed distant metastases. Distant spread of the tumor without lymph node involvement was observed during follow-up in 4 cases. Nine patients died of disease, 2 are alive with widespread metastases, 2 are alive with no evidence of disease, and 2 have died of other causes. The determined 5-year survival was estimated to be 17.5% by the Kaplan-Meier method. In conclusion, BSCC is a distinctive carcinoma that is important to recognize, because it has a more aggressive biological behavior than conventional squamous cell carcinoma.