Aim of this study was to investigate whether intranasal anatomy plays a role in intranasal trigeminal sensitivity. A total of 65 healthy subjects (30 female, 35 male) participated in this study (age range 18-35 years). Nasal cavities were assessed using magnetic resonance imaging (MRI). The area of the nasal cavity was measured in 5 coronal sections distributed across the length of the nasal cavity. Trigeminal function was assessed by determining thresholds for CO2, and responses to suprathreshold stimulation with CO₂ and menthol (intensity ratings; eventrelated potentials). In addition, rhino-manometric measures were obtained. A positive correlation was found between the size of the nasal cavity and trigeminal event-related potentials in response to suprathreshold CO₂ and menthol stimuli. By contrast, no such correlations were found between nasal cavity size and CO₂ thresholds. Results from rhino-manometry correlated only with the size of the nasal cavity in the nasal valve area. These data suggest that, at least at a suprathreshold level, nasal anatomy plays a significant role in determining interindividual differences in the sensitivity to trigeminal stimuli.