A subdural hematoma was found to accompany neuronal ceroid lipofuscinosis in an 11-month-old Dachshund. Results from clinical, magnetic resonance (MR) imaging, histopathologic, ultrastructural, and molecular assessments are described. The dog had a 3-month history of progressive neurologic signs. In MR images, there was severe asymmetric cerebral atrophy with a subdural hematoma. Histopathologically, there was autofluorescent, periodic acid-Schiff-positive lipopigment in neurons and transmission electron microscopy confirmed a typical curvilinear profile of the storage bodies. We hypothesize that rapid brain atrophy contributed to the subdural hematoma formation, a complication not described previously in dogs with neuronal lipofuscinosis.