We aimed to investigate the relationships among concha bullosa (CB), nasal septal deviation (NSD), and sinus disease. We retrospectively reviewed paranasal sinus computed tomography scans obtained from 296 patients-132 men and 164 women, aged 17 to 76 years (median: 39)-who had been evaluated over a 19-month period. CBs were classified as lamellar, bulbous, and extensive. In cases of bilateral CB, the larger side was designated as dominant. In all, 132 patients (44.6%) exhibited pneumatization of at least one concha, 176 (59.5%) had NSD, and 187 (63.2%) had sinus disease. Some 89 of 106 patients with unilateral or one-side-dominant CB (84.0%) had NSD, 89 of 132 patients with CB (67.4%) had sinus disease, and 109 of the 176 patients with NSD (61.9%) had sinus disease. We found a statistically significant relationship between CB and contralateral NSD, but no significant relationship between CB and sinus disease or NSD and sinus disease. While CB is a common anatomic problem that may accompany NSD, a causal relationship between CB or NSD and sinus disease is dubious.