Abstract: A door frame made of synthetic material having an elongated, horizontally-oriented head and an elongated, horizontally-oriented sill, spaced apart from the head portion. The head and sill are preferably single, continuous members. The door frame also has at least two spaced apart, vertically-oriented jambs, each connected at one end to the head and at an opposite end to the sill. The jambs have a cavity disposed vertically therethrough. A rigid supporting member is then provided within selected jamb cavities. The rigid supporting members are preferably made of metal, such as aluminum, aluminum alloys and ferrous and non-ferrous materials. The jambs may further have more than one cavity disposed vertically therethrough, so that more than one supporting member is provided in a jamb.