A wavelength-division-multiplexing transmission experiment using a 1300/1500 nm dual-wavelength LED modulated at 140/560 Mbit/s over 10 km of single-mode fiber has been demonstrated. This dual-LED device has a 9 mu m emitter spacing between the active facets with a coupling loss of 2. 3 db through a lens/fiber coupler. The chromatic dispersion penalty for the 1500 nm channel at 560 Mbit/s was about 6. 5 db and the electrical crosstalk penalty was 2. 5 db.