In this paper, the use of a real-time perceptual speech quality metric (RTPSQM) in power control of the Universal Mobile Telecommunication System (UMTS) is investigated. It is shown that with this approach the efficiency of the power control techniques in UMTS is improved. In particular, the average Signal-to-Interference Ratio (SIR) target can be reduced by the proposed RTPSQM-based power control compared to the conventional algorithm while keeping the perceptual quality in the desired range. This benefit can be large for particular shadowing profiles.