The trigeminal and olfactory nerves share overlapping innervation areas in the nasal cavity and seem to work in an interactive way. Loss of olfactory function leads to a decreased trigeminal sensitivity, as shown in anosmic subjects. To report the impact of disturbed trigeminal sensitivity on the olfactory function, we present a patient with unilateral loss of trigeminal function resulting from a meningeoma. Thresholds to a selective olfactory stimulus were elevated by a factor of 64 on the affected side. Recordings of event-related potentials in response to olfactory stimuli showed a significantly reduced response on the affected side. This report indicates that loss of trigeminal function may affect the sense of smell.