Morphological variability of paranasal sinuses is well known for endoscopic surgeons and anatomists alike. The ethmoid sinus is the most complex and variable of all paranasal sinuses, due to the fact that its development is not yet well known and is influenced by many factors. Volumetric studies of the sinuses have been made using dried skulls, cadaver heads and imaging studies, but there are still not sufficient data in order to name a standard value for each sinus. Few data can be found especially regarding the ethmoid sinus. In this paper, we measured the volumes of ethmoid lateral masses, and for anterior and posterior groups of cells, using imaging studies and a volumetric feature of our imaging studies. Results showed an average volume between 7.34 cm3 and 8.39 cm3 for the ethmoid lateral mass, between 4.33 cm3 and 4.92 cm3 for the anterior ethmoid and between 3.01 cm3 and 3.47 cm3 for the posterior ethmoid groups. We also found that the average volume of the anterior ethmoid occupies between 58-59% of the whole volume, while the posterior ethmoid occupies only 41-42% of this volume.