A method for measuring the noise factor (FDUT) of a device under test, which requires exclusively a network analyzer. The noise factor (FDUT) is calculated from the internal noise (NNWA) of the network analyzer determined in a calibration process, the power amplification (GDUT) of the device under test determined by measuring the S-parameters of the device under test, and the measured value (PNOISE) of the noise output (NNWA) applied at a first gate of the device under test without exciting the device under test with a noise signal.