Selected tarsal bristles of the tick Amblyomma americanum (L.) (Acarina: Ixodidae; nymphal stage) were studied by means of scanning and transmission electron microscopy. All sensilla are multi-innervated and have thick cuticular walls containing either an elaborate pore canal system or a single slit opening at the tip. These sensilla, often equipped with two mechanoreceptive dendrites attached to the bristle base, apparently serve a dual function: mechano- and chemoreception. The fine structure of each sensillum is similar to that of other arthropod setae except for the ciliary region of the dendrite. Instead of the common 9 double-tubules, the tick sensilla usually have 11 (“11+0”). Compared to insect or spider tarsal bristles, tick setae are less abundant but more complex in structure and of greater variety.