The effect of a transparent Pt metal layer on optical and electrical performance of InGaN/GaN multiple-quantum well Light-Emitting Diodes (LEDs) was investigated. The light output power for the LED with a transparent metal layer is significantly enhanced compared to that for the LED without one over all the current ranges investigated. Below a thickness of 10 nm of the transparent Pt metal layer, the relative external quantum efficiency of an LED sample saturates at a lower current level due to the high resistivity of the thin transparent Pt metal layer. The present results suggest that, for efficient LEDs, the transparent Pt metal layer should have a minimum thickness >10 nm. (C) 2003 The Electrochemical Society.