During multisensory experiences, visual stimuli typically suppress non-visual stimuli. Such ”visual dominance” effects might stem from inhibition across sensory systems. Does visual dominance generalize to odor-visual pairings? We developed a categorization task (fruits vs flowers) with congruent and incongruent odor-picture pairings and a delayed auditory response target that informed about categorization modality (olfactory vs visual). We investigated behavioral and cortical (ERP) responses. For congruent pairings, we found better accuracy for visual decisions. However, for incongruent pairings, we insteadobserved faster RTs for olfactory decisions. Incongruent olfactory stimuli thus interfere more with visualdecisions than vice versa. Our ERP results from auditory targets on incongruent trials gave supporting evidence of olfactory suppression over visual perception; higher P300 amplitudes were more strongly correlated with faster RTs during visual categorization. A late “slow wave” ERP effect had later onset andlonger latency during visual vs olfactory decisions. This indicates that in order to rapidly and successfully categorize visual stimuli (and ignore incongruent odors), participants need to allocate additional attentional and working memory resources. In sum, both behavioral and ERP effects suggest a higher level of interference from incongruent olfactory, compared to visual, input. These findings suggest that asymmetric inhibition across sensory systems is a fruitful way of studying sensory dominance, and that olfactory stimuli can dominate visual stimuli, refuting the general notion of ”visual dominance”.