This article presents a preliminary report on the excavation campaigns of 1999 to 2001 conducted in the Sanctuary of Apollo Phanaios at Kato Phana on Chios by the 20th Ephorate of Prehistoric and Classical Antiquities in collaboration with the British School at Athens. An account of the stratigraphy and architectural remains encountered is first presented, followed by a selected catalogue of the ceramic and small finds. The report concludes with a discussion of the chronological development of the site. While prior to the resumption of excavation work at Kato Phana in 1999 it was commonly held that the sanctuary had been established in the Late Geometric period, the new finds suggest that the history of cult worship here may extend back to the Late Mycenaean and the subsequent Protogeometric, Early Geometric and Middle Geometric periods. Excavation results now also reveal that by the seventh century BC the sanctuary had been architecturally embellished with permanent stone structures, with further architectural remodelling taking place on at least two subsequent occasions during the Archaic period. Though the paucity of Classical, Hellenistic and Roman finds from the site is puzzling, the Early Christian period provides a wealth of ceramic and small finds and architectural remains.