In Ottoman bath architecture, the dome is the spherical structural component covering the square planned dressing hall, warm and hot spaces. In this study, the relationship between bond type, dome span, dome height, dome thickness, and the number of oculi of domes in some Ottoman baths located in Western Anatolia (Turkey) were investigated for the purpose of evaluating construction techniques and architectural characteristics. The studied domes were constructed with brick and lime mortar as binder. In the construction of domes, whole and half bricks with different dimensions were used. In all domes, the surfaces were covered with brick-lime plaster, a thin layer on the interior and a thick layer on the exterior. Terracotta pipes placed in the brick bond or the openings made through the brick bond constituted oculi for lighting. Depending on the brick bond, a linear relationship was determined between the span, height, and number of oculi, whereas a mathematical ratio between 1: 10 and 1: 12 was determined between the span and thickness of the domes. It has also been noted that as the dome span increases, so does the height, thickness at the springing level and the number of oculi. The domes examined with these properties should be seen as historical documents representing the construction technology of the 15th century. Therefore, these properties of domes must be preserved and special care needs to be taken as not to lose the original qualities of these domes during conservation works. (C) 2013 Elsevier Masson SAS. All rights reserved.