Background: The aim of this study was to investigate the diameters of the bony nasolacrimal canal by computed tomography in normal adult Mongolian population and the effect of gender and age on the nasolacrimal canal diameter. Methods: Using standart tomographic images, we measured the diameters, angle between the bony canal and nasal floor and length of the bony nasolacrimal duct in 150 patients without nasolacrimal duct disease. Results: The anterioposterior diameter of the bony nasolacrimal canal was 6.49± 1.06mm, transverse diameter was 4.56±0.9mm, angle between the bony canal and nasal floor was 69.6±8.1o. No significant difference in anterioposterior diameter and transverse diameter in gender. The angle between the bony canal and nasal floor was significantly greater in male. Conclusions This study may contribute to the establishment of a detailed anatomical and morphometric baseline of the bony nasolacrimal canal and provide useful information for the planning of interventions for nasolacrimal duct obstruction