© 2020 British Epilepsy AssociationPurpose: The temporal lobe plays an important role in the perception of odors. Another important anatomical structure involved in the perception of smell is the olfactory bulb. The relationship between olfactory bulb volume (OBV) and olfactory function is unclear, however. In our study, we aimed to evaluate the relationship between OBV and olfactory function in patients with mesial temporal lobe epilepsy (MTLE). Method: Forty-eight patients with MTLE who were managed in the Cerrahpaşa Medical Faculty Neurology Department's epilepsy outpatient clinic were recruited for the study. Tests with Sniffin’ Sticks and Taste Strips were performed and OBV measured in all patients. Two control groups were recruited, one for the Sniffin' Sticks and Taste Strip tests and one for OBV measurement. Results: In the smell tests; the threshold, discrimination and identification scores were significantly lower in the MTLE group than in the control group. The mean taste test scores did not differ significantly between the MTLE and control groups. In the MTLE group, the mean right OBV was 40.2 ± 12.54 and the left OBV was 39.3 ± 10.54, both of which were significantly lower those in the control group. The mean OBVs of patients with hyposmia were significantly smaller bilaterally than the OBVs of those with normosmia. There was no correlation between the gustatory scores and OBV. Conclusions: Olfactory function was significantly impaired in patients with MTLE compared with healthy controls in all domains, namely threshold, discrimination, and identification. In addition, olfactory bulbus volume was smaller in patients with olfactory dysfunction.