Abstract: The invention relates to a method and arrangement for target seeking, where a rotatable instrument emits an electromagnetic radiation and automatically searches for a target reflector by detecting whether reception occurs of electromagnetic radiation received by the target reflector and reflected back to the instrument. In the beam path of the electromagnetic radiation, polarization of the electromagnetic radiation, polarization modulation of the polarization direction on the electromagnetic radiation by alternately changing it, and polarization of the electromagnetic radiation take place in sequence. At least on of these steps is performed at the target reflector. Checking of the detected reflector is carried out by testing if the received radiation changes at the same rate as the modulation of the polarization direction. Only targets are accepted which give different signal strengths at said rate for the received radiation.