Intestinal-type adenocarcinoma (ITAC) of the nasal cavity and paranasal sinuses may occur sporadically or as an occupational-related hazard, especially in cases of wood dust exposure. The clinical and pathologic features of 17 cases of sporadic-type ITAC are presented and compared to those among woodworkers. Both groups are analyzed collectively to define further the biological spectrum of this rare neoplasm. Histologically, five variants of ITAC were recognized: papillary, colonic, solid, mucinous, and mixed. The nine men and eight women in this series ranged from 31 to 80 years of age. Eight tumors originated in the maxillary sinus, seven in the nasal cavity, and two in the ethmoid sinus. Unilateral nasal obstruction and epistaxis, averaging 6.8 months in duration, were the most common symptoms. At least four of the patients are known to have died of their disease. In contrast, ITAC in woodworkers occurs primarily in men, originates almost exclusively in the nasal cavity or ethmoid sinus, and has a better prognosis. Data pooled from 213 cases of ITAC indicate that 53% of patients have experienced local recurrences following therapy, 8% (range 0-22%) have developed cervical lymph node and 13% (range 0-29%) distant metastases, and 60% have died of their disease. Of those dying, 80% did so within 3 years of diagnosis (range 1 month to 9.1 years).