Purpose To compare the morphological features of the bony nasolacrimal canal (NLC) in Caucasian adults with and without primary acquired nasolacrimal duct obstruction (PANDO). Methods The study included one eye each from 38 patients with PANDO and 38 age- and gender-matched controls without PANDO, all of whom underwent multidetector computed tomography. In tomographic images, length, and orientation angles of the NLC, transverse canal diameters at the duct entrance and lower end, and minimum (narrowest) transverse and anterior-posterior canal diameters were measured. Results The two groups were similar for NLC length and angulations. The transverse entrance diameter was significantly narrower in the PANDO group (mean, 4.6 mm vs. 5.1 mm) (p = 0.09). The narrowest site was most frequently in the middle duct or slightly above the middle in both groups (p > 0.05). The minimum canal diameters were significantly smaller in the PANDO group (p = 0.010 and p = 0.003). When gender subgroups were compared, the significant differences continued for the transverse entrance and minimum diameters in females with PANDO (p = 0.006) and for the minimum anterior-posterior diameter in males with PANDO (p = 0.02). Conclusion Narrowness of the upper and/or middle part of the bony nasolacrimal duct may play a role in the development of PANDO in the adult Caucasian population.