A window frame for installation in the exterior shell of an aircraft, which comprises one outer flange, an inner flange, and a vertical flange extending between flanges. A window frame is fixed in its position via a plurality of holder elements being arranged substantially equidistance from each other over the periphery of the window frame, being distributed on the outer flange of the window frame. Each of the holder elements comprises a base plate having a face, a pin, a pin extending outwardly from the face of the base plate and a pin to, a downholder clip. The clip may be adapted for a press fit engagement with the pin. The outer surfaces of the pin include a sawtooth-like structure, which engages with hook-shaped clamping elements flexibly formed on the downholder clip and over which an annular locking element is displaced. The holder elements may include a thermoplastic material, which may be provided with reinforcement fibers and may be die cast. Before installation of the window frame in the aircraft, the base plates of the holder elements are adhered to the outer flange of the window frame, and upon mounting of the window frame to an aircraft structure, the outer flange is riveted to an exterior shell of the aircraft.