Testing a transceiver

The invention relates to a method and an arrangement implementing the method for testing a transmitter part (100) and receiver part (102) in a transceiver. A signal in the transmitter part is mixed with a mixing signal for generating a signal to be connected to the receiver part, which generated signal is connected to the receiver part and said connected signal is compared with the transmitter part signal to test the transceiver. The mixing signal is generated by connecting a signal generated by means of a signal generator (202) used in the operation of the transmitter part and/or receiver part to at least two signal branches, dividing the signal in the signal branches into at least two signals of different frequencies in the different signal branches, and generating a mixing signal from the signals of different frequencies.