Double-heterostructure InP/lnGaAsP/lnP high-radiance l.e.d.s have been fabricated by liquid-phase epitaxy on the face of commercially available InP substrates. The best small-area l.e.d.s had a useful external power efficiency of 1.5% and a 900 Å-wide emission spectrum centred at 1.23 μm. emitting ∼3 mW into the air at 100 mA and 2 V; essentially similar results were obtained with devices operating al 1.30 μm.