The effect of endogenous attention on the detectability of weak flavorants was examined in an absolute detection (two-alternative forced-choice) task. Attention to sucrose improved the detectability of sucrose, a gustation-based flavorant, both when the alternative was water and when it was vanillin. But attention to vanillin did not improve the detectability of vanillin, an olfaction-based flavorant, either when the alternative was water or when it was sucrose. Nor did attention improve the detectability of vanillin when the alternative was citric acid, a tastant that is qualitatively less similar to vanillin than is sucrose. Attention had no positive effect on the detection of either sucrose or vanillin when it was mixed with the other substance. These findings suggest that although it is possible to attend selectively to gustatory flavors, it may be more difficult to attend selectively to olfactory flavors--perhaps because attention to flavors, which are taken in the mouth, is directed spatially toward the tongue, where gustatory, but not olfactory, receptors are located.