The Phthie (in Greek old Φθίη / Phthíê , modern: Fthíi ) or Phthiotide (in Greek modern: Φθιώτιδα / Fthiótidha , old Greek: Φθιώτις / Phthiôtis ) is an old area of ancient Greece, located at the south-east of the Thessalie, at the bottom of the Lamiaque gulf. Its capital was, according to Homère, the city of Phthia - no vestige was found by it. Inhabited by the Myrmidons, it was the kingdom of Pélée, its son Achille and his grandson Néoptolème. It was then an Achaean ground .

It is in Phthie that the procession of the Thermopyles is.

The Phthiotide is also a names current Greece, more reduced than the old area. It has as a chief town and only big city Lamía which is a center commecial and a node of communications. It is a mainly agricultural area: Cotton, Rice and cereals especially. It is crossed by the Sperhios river.