Long-term olfactory dysfunction after COVID-19 is becoming an increasingly worrying symptom of post-COVID syndrome. Three years after the onset of the pandemic, still little is known about the mechanism behind the long-term olfactory impairment experienced by many patients. The olfactory bulb (OB) is the first region where olfactory information enters the brain. Studies have shown abnormalities in OBs of early COVID-19 patients, however, follow-up is lacking. We aimed to quantify OB volume in patients with COVID-19 related olfactory dysfunction over time, and compare to healthy controls. This preliminary analysis was performed with 11 COVID-19 patients with olfactory dysfunction, and 11 healthy subjects (Sniffin’ Sticks score > 30.5) matched on gender and age. All subjects were scanned with MRI, using a specialized T2 weighted sequence to image OB (28 slices, slice thickness: 1 mm). Patients in the COVID-19 group were scanned twice, once within 6 months of their original infection (T1), and 6 months later (T2). At T1, mean Sniffin’ Sticks score for the COVID-19 group was 22.8, and 24.6 at T2. Manual segmentation of the left and right OB was performed on each slice of the MRI-scan where the bulb was visible. Consequently, volume in mm3 was calculated. There was no significant difference in total OB volume between T1 (94.0 mm3) and T2 (106.0 mm3) for the COVID-19 group (p=0.12). Similarly, a two-sample t-test between the COVID-19 group and healthy patients (114.5 mm3) showed no significant differences in total OB volume (p=0.12 at T1, p=0.50 at T2). A moderate positive correlation was found between Sniffin’ Sticks score and total OB volume when all measurements were grouped together (r(20)=0.49, p=0.02). Overall, OB volume and olfactory function are in line, albeit not significant, indicating a trend towards recovery over time. Updated results including more participants in both groups will be presented at the conference. Funded by ZonMW: 10430102110001.