This book documents the first hypothesis of phylogenetic relationships within subtribe Aeridinae and should be considered preliminary. Nevertheless, results indicate that subtribe Aeridinae is one of the most taxonomically complex groups in orchids. Further phylogenetic analyses with more molecular markers and greater taxon sampling are desirable to establish more robust phylogenetic hypotheses for the subtribe. However, the phylogenetic relationships as well as revised classification scheme presented here provide framework for further systematic and taxonomic investigations of the subtribe. Particularly, there were found some unexpected relationships in this study, and putative morphological synapomorphies for these relationships are not understood. A reinvestigation on the basis of the phylogenetic scheme presented here will shed more light on overlooked characters.