The invention relates to a method of performing handover in a mobile radio system. The mobile radio system performs quality measurements on signals transmitted (300) between a mobile terminal and predetermined radio base stations. Handover is performed (301, 302, 303) when some of the measured signal strengths exceeds the signal strength for the radio base station to which the mobile terminal for the moment is set up, added to a handover value. The handover value is dependent on measured signal strengths and neighboring cell relation values. The neighboring cell relation values depend on a probability for handover to be performed from one radio base station to another radio base station in the mobile radio system.