Arkoi (Greek: Αρκοί; also Arkioi (Αρκιοί)) is a small Greek island in the Dodecanese archipelago, located east of Patmos, north of Leipsoi and southwest of Agathonisi. The island belongs to the municipality of Patmos, which is part of the South Aegean region, and had a population of 54 inhabitants at the 2001 census.
The small population means that there is no real capital, but most inhabitants live close to the main harbour with the rest living scattered around the island on higher ground. The majority of the population finds employment in fishing, merchant shipping, goat herding or running one of the island's four tavernas.