Abnormal chemosensory perception has been identified as a possible mechanism underlying odor intolerance, but research in this domain has yet been rather limited. The main objective of the present study was to investigate total perceived intensity, unpleasantness, sensory irritation, and cortical activity assessed with chemosensory event-related potentials (ERPs) for three concentrations of pyridine ranging from predominantly olfactory to trigeminal in activation. Results from 19 individuals with self-reported chemical hypersensitivity and 19 controls with self-reported normal chemical sensitivity show that the hypersensitive group, compared to controls, rated the pyridine stimuli to be more intense and unpleasant, and that these group differences increased with pyridine concentration. Sensory irritation was also the perceptual dimension found to correlate strongest with score on the Chemical Sensitivity Scale. However, no group differences were found in ERP amplitudes or latencies. These findings suggest that self-reported chemical hypersensitivity (1) can be associated with anormal chemosensory perception, (2) may be more closely related to trigeminal function than to olfaction, and (3) has a neural basis at a higher cortical level than that captured by chemosensory ERPs. (C) 2004 Elsevier B.V. All rights reserved.