A high quantum efficiency for a porous silicon light-emitting diode (LED) is demonstrated. The LEDs, fabricated by anodic etching from a p(+)nn(+) structure, exhibit external quantum efficiencies of similar to 0.2% under pulsed operation. Corresponding internal quantum efficiencies of a few percent approach those of the photoluminescence. The color of the emitted light can be tuned from orange to the infrared range by variation of etching parameters in agreement with the quantum confinement model. The spectral distribution is voltage independent, as well as the quantum efficiency for voltages above 20 V.