Tuberculous infections of the nasal cavity and paranasal sinuses are rare, as are descriptions of their radiologic findings, including those of CT. The authors recently encountered two cases of tuberculosis which developed in the paranasal sinus and the nasal cavity. Both were diagnosed by means of tissue biopsies taken from the mucosa of the maxillary sinus during endoscopic sinus surgery and Caldwell-Luc 's operation, respectively. In one case biopsy revealed caseous epitheloid granuloma, shown on histopathological examination to be consistent with tuberculosis. The other case involved a patient with pulmonary tuberculosis, in which nasal biopsy showed the presence of chronic granulomatous inflammation. In both cases CT scanning revealed a heterogeneous enhanced soft tissue mass in the paranasal sinus and nasal cavity, and associated findings consisting of surrounding bony thickening of the maxillary sinus and focal bony erosion or destruction were noted. CT findings of the latter showed prominent mass extension to the skull base, which was difficult to differentiate from the tumorous condition of the sinonasal cavity. After taking antituberculous medication for about two months, both patients showed substantial improvement.