Twenty patients (18 males, 2 females) with lepromatous leprosy and 10 age- and sex-matched controls were subjected to computed tomographic (CT) scans of the paranasal sinuses (PNS). The mean bacterial (BI) and morphological indexes were 3.4+ and 1%, respectively. Nasal symptoms were present in nine (45%) patients; 15 (75%) out of 20 patients showed significant abnormalities on CT scans of the PNS compared to none of the 10 controls. The maxillary and ethmoid sinuses were affected in 11 (55%) patients each, followed by the sphenoid sinus in four (20%) patients. Frontal sinus involvement was least frequent, only one (5%) patient showed CT changes. Mucosal thickening was the most common finding followed by soft-tissue densities and, rarely, a fluid level was seen in the PNS. Involvement of the PNS correlated with a high BI of 4+ or more (75% vs 37.5%). Paranasal sinus involvement is an integral part of lepromatous leprosy since histological involvement was present even when the CT scan was apparently normal.