The ixodid tick Haemaphysalis longicornis Neumann, a broadly western Pacific species, is the only economically important tick that has successfully invaded New Zealand. Species sympatric with it could also pose a risk to New Zealand as potential invaders because they share bioclimatic and host preferences with H. longicornis. At least 15 of the 45 species of Ixodidae and one Argasidae discussed here as sympatric with H. longicornis, and which most closely match its bioecological characteristics, pose the highest risk. These include: Amblyomma breviscutatum, Dermacentor reticulatus, D. silvarum, Haemaphysalis hystricis, H. papuana, Ixodes acutitarsus, I. cornuatus, I. holocyclus, I. nipponensis, I. ovatus, I. persulcatus, I. ricinus, I. tasmani,Rhipicephalus haemaphysaloides and R. sanguineus. The principal countries of origin of these species are Japan, China and Australia, and in each case humans could be an unwitting vehicle of entry. Sympatry and shared biological preferences are not necessarily indicative of potential invasiveness, but serve as indicators of the need for heightened surveillance.