Electroluminescence has been observed from Si(1-x)Ge(x)/Si p-n heterostructures grown by molecular beam epitaxy and fabricated into mesa diodes. The luminescence from each sample was observed at temperatures up to 80 K with diodes forward biased at current densities up to 50 A/cm2. For x = 0.18 and x = 0.25, broad (approximately 80 meV) electroluminescence peaks were observed at 890 and 860 meV, respectively. These energies as well as the peak shapes and quantum efficiencies (approximately 1%) were the same as those from corresponding photoluminescence spectra.