Indications of adverse effects of nontoxic malodorous chemical exposure on work performance and safety and the role of health-risk perception on odor perception motivated the present study of the impact of health-risk perception on odor perception and cognitive performance. Healthy young adults were informed that they were to be exposed to an odorous substance that is either potentially health-enhancing (positive information bias, n = 24) or hazardous (negative information bias, n = 25). The two groups, screened for loss in odor-detection sensitivity, were matched for age, sex, chemical intolerance, and negative affectivity. During each of 14 trials of exposure to 433 mg/m(3) of n-butanol, the participants rated the intensity and valence of odor perception and performed a cognitive task that taxed working memory and attention. The results showed that the negative-bias group rated the odor perception as more unpleasant than did the positive-bias group during the entire session, but significantly more unpleasant only during the first half of the session. The negative-bias group was also found to perform significantly poorer on the cognitive task during both halves of the session. No effect of information bias was found on perceived odor intensity. The results provide experimental support for the hypotheses that belief that exposure to an odorous chemical is hazardous contributes to the odor perception being more unpleasant and to poorer cognitive performance.