To investigate the factors influencing the volume of the olfactory bulb (OB) in patients with post-viral olfactory dysfunction (PVOD).We collected 92 olfactory bulb volumes from patients with PVOD who underwent a sinus computed tomographic and magnetic resonance imaging (MRI) scan of the head and collected clinical information including gender, age, disease course, minimal cross-sectional area, nasal airway resistance, and olfactory function. OB volume was measured in MRI and the scans were evaluated according to the Lund-Mackay (LM) scoring system.Male patients with PVOD had a larger OB volume (β = 0.284, P < 0.05). OB volume was smaller in patients with a longer course of olfactory dysfunction (β = - 0.254, P < 0.05). According to the LM scoring system, patients with a higher anterior ethmoidal sinus score had smaller OB volume (β = - 0.476, P < 0.05).The study revealed that gender, disease course, and the score of anterior ethmoidal sinusitis can affect the OB volume in patients with PVOD.© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.