Abstract The larval stage of Amblyomma pacae Aragao is described using optical and scanning electron microscopy. Unfed larvae were obtained from a colony of A. pacae originating from engorged females collected on Agouti paca (Linnaeus) from Monte Negro County, state of Rondonia, Western Amazon, Brazil. Several morphological characters are described for the first time, including the chaetotaxy of the idiosoma, palpi and Haller's organ, as well as morphological features of the idiosoma, gnathosoma and legs. The topographical and numerical patterns of integumentary pores (porotaxy) of the larva are described using a recently proposed nomenclature. Only a few morphological differences were observed between the A. pacae larva and other Amblyomma spp. larvae previously described from Brazil; however, some of these characters can be used to differentiate A. pacae from other species of this genus.