BACKGROUND: Previous work suggests differences in the distribution of human intranasal trigeminal receptors. The aim of this study was to investigate these topographic differences for different concentrations of different trigeminal irritants using an electrophysiologic measure of trigeminal activation, the negative mucosa potential (NMP). MATERIALS AND METHODS: A total of 15 healthy volunteers participated. Presented by a computer-controlled olfactometer CO2 (30% and 40% v/v), ethyl acetate (5.5% and 9.3% v/v) and acetic acid (205 and 40% v/v) were used for stimulation. NMP was recorded at the middle septum, the middle turbinate, and the floor of the nasal cavity. RESULTS: Maximum amplitudes of the NMP were found at the middle septum and were lowest at the nasal floor. Response amplitudes were related to stimulus concentrations. There was no significant difference between responses to the three different stimuli in relation to three recording sites. CONCLUSIONS: In agreement with previous work, the present data suggest that there are topographic differences in the responsiveness of the mucosa to chemical irritants.