the aim of this study was to assess the effectiveness of cashew nut shell liquid (cnsl), cordia verbenacea and psidium guajava, both alone and in association against rhipicephalus microplus. larval packet and adult immersion tests were conducted in concentrations ranging from 3.1 at 100.0mg ml-1. cnsl was effective against engorged females (99.6%) at 100.0mg ml-1 and against larvae (99.2 %) at 50.0mg ml-1. the highest efficacy on engorged females was achieved by the essential oils of p. guajava at 12.5mg ml-1 (99.9%), followed by those of c. verbenacea at 25.0mg ml-1 (96.9%), while a low larvicidal activity of 5.8 and 59.0% was, respectively, obtained. the association at 50.0mg ml-1 had asignificant effect on both life stages of r. microplus. this association caused considerable larval mortality (95.3%) and high efficacy on engorged females (93.9%).