A method for calibrating a network analyzer having at least two test ports is described in which a completely known, transmitting first calibration standard, is designed as a two-port standard and is connected between two test ports of the network analyzer, is measured. Also measured is a second calibration standard that is designed as a two-port standard or a double one-port standard and is connected between the same test ports of the network analyzer, of which only the reflection parameters are known. Measured too is a third calibration standard, symmetrical with regard to its reflection parameters and designed as a two-port standard or a double one-port standard and is connected between the same test ports of the network analyzer. From results of these measurements, the matrix elements of error two-ports assigned to the test ports are calculated.