Objectives Involuntary tearing is an annoyingly common consequence of cutting onions. Little is known about who experiences so-called "onion tears" and to what extent they experience them. Our aim with this study was to explore whether the degree of onion tearing is a phenotypic predictor of olfactory function and trigeminal sensitivity, assessed by both self-report and psychophysical measures of chemosensory function.Methods A total of 1001 participants (598 females; Mage 44 years) completed four subjective ratings of nasal function (subjective smelling ability, nasal sensitivity, trigeminal sensitivity, and nasal patency), three psychophysical tests (odor identification, AmmoLa intensity, and odor lateralization), and answered questions about the severity of their tearing while cutting onions.Results Results revealed that higher levels of onion tearing were associated with better self-rated olfactory ability, nasal breathing, and higher sensitivity to nasal stinging/burning. No statistically significant relationship was found between the psychophysical tests of olfactory ability and degree of onion tearing. Performance on all measures was also analyzed across three different age brackets (18-35; 36-55; 56+ years) and yielded mixed findings related to subjective ratings of trigeminal sensitivity and olfactory function.Conclusion Clinically, there is yet to be a universally accepted measure to determine subjective chemosensory sensitivity, and in particular, trigeminal sensitivity. Despite inconsistencies between the subjective and objective chemosensory tests, our findings suggest that asking someone about the severity of their tearing while cutting onions may be a useful addition to standard testing assessing chemosensory and trigeminal sensitivity.Level of Evidence 3.