Several methodologies have been proposed to assess the orbital volume (OV). However, we have not seen a criterion standard study evaluating the results of the methodologies for the assessment of OV In the current study, the actual OV of 9 dry skulls was measured using the water filling method as the criterion standard. Consecutive computed tomographic sections at a thickness of 1.5 mm were used to estimate the OV by means of the point counting method. The mean (SD) of the OV measured by the water filling method was 17.84 (1.56) cm(3). By using the point counting method, it was 17.05 (1.69) cm(3). There was no statistically significant difference between sides (P > 0.001). The results of the OV values obtained by the two methods were compared statistically. The agreements between the two methods were also evaluated using the Bland-Altman plots. There was no statistically significant difference between the OV measurements obtained by the stereological technique and water filling method. The described method could be used for the assessment of OV in vivo.