BACKGROUND: Developmental disturbances of the paranasal sinuses are proposed as the cause of osteoma. We examined whether such disturbances may result in the frequent presence of anatomical variations of the paranasal sinuses in patients with osteoma. METHODOLOGY/PRINCIPAL: The study was performed retrospectively on 2,820 patients subjected to CT examination during 2005 - 2011. Demographic and CT characteristics of osteoma, and associated pathological findings were evaluated for 104 patients with diagnosed osteoma. The presence of anatomical variations was assessed for 51 osteoma patients with a complete medical history, and for 1,233 patients from a control group. RESULTS: The prevalence of osteomas was found to be 3.69%, with male to female ratio 1.08:1. The frontal sinus was most commonly affected. The presence of anatomical variations was more frequent in patients with osteoma than in controls, with significant differences confirmed for the sphenomaxillary plate, infraorbital cell, and crista galli pneumatization. CONCLUSIONS: The paranasal sinus osteoma is associated with higher prevalence of anatomical variations. This can be explained either by the stronger influence of genetic and/or environmental factors on the development of the paranasal sinuses in patients with osteoma, or by their higher susceptibility to above mentioned factors.