Abstract: Haplopelma lividum and H. longipes (Araneae: Mygalomorphae: Theraphosidae) are tarantulas that are distributed throughout Southeast Asia and are important carnivorous predators in ecological systems. The present study aimed to examine the phylogenetic relationships between Mygalomorph spiders using 28S ribosomal DNA sequences. The molecular results supported the placement of both species within a common theraphosid taxon. However, when considering relationships between Haplopelma spp. and related genera, H. schmidti, H. lividum and H. longipes were not monophyletic, suggesting that molecular data are incongruent with phylogenies based on morphological characteristics. These results provide molecular data to help elucidate the phylogenetic relationships between theraphosid tarantulas.