For the understanding of the CT findings of polymorphic reticulosis involving the upper respiratory tract, we reviewed eleven cases of this disease with initial CT study before treatment. CT revealed masses or swelling in the nose or nasal chamber, often with involvement of paranasal sinuses and medial parts of the orbit. In some, nonspecific minimal bony change (either bone destruction or bone sclerosis) was found. These CT findings are not specific. Any large mass in the nose and nasal fossa with little associated bone destruction should, however, raise the differential diagnosis of polymorphic reticulosis.