Aphids, aphid plant host, and ant associations in the major islands of Palau were documented from collections made during 2000-2001 and 2003-2004. None of the collected aphids and ants were indigenous to Palau. Ten aphid species were recorded: Aphis craccivora Koch, Aphis gossypii Glover, Astegopteryx bambusae Buckton, Astegopteryx esakii (Takahashi), Astegopteryx rhapidis (van der Goot), Hyalopterus pruni (Geoffroy), Hysteroneura setariae (Thomas), Pentalonia nigronervosa Coquerel, Rhopalosiphum maidis (Fitch), and Tetraneura spp. Twenty seven ant species were recorded: Anoplolepis gracilipes (Smith), Brachyponera croceicornis (Emery), Camponotus chloroticus Emery, Camponotus reticulatus Roger, Camponotus navigator Wilson, Cardiocondyla emeryi Forel, Cardiocondyla. wroughtonii (Forel), Eurhopalothrix procera (Emery), Iridomyrmex anceps (Roger), Monomorium floricola (Jerdon), Monomorium monomorium Bolton, Odontomachus simillimus Smith, Paratrechina bourbonica (Forel), Paratrechina longicornis (Latreille), Pheidole fervens Smith, Pheidole megacephala (F.), Pheidole umbonata Mayr, Pheidole sp., Polyrhachis dives Smith, Pyramica karawajewi (Brown), Solenopsis geminata (F.), Tapinoma melanocephalum (F.), Tapinoma sp., Technomyrmex albipes (Smith), Technomyrmex sp., Tetramorium bicarinatum (Nylander), and Tetramorium lanuginosum Mayr.