Abstract. Lead-rare earth-chalcogenide diode lasers have been grown by molecular beam epitaxy. Emission wavelengths shorter than 5 to 6 Am have been obtained from lead-europium-selenide-telluride (Pb1 -xEuxSeyTe1-y) double heterojunction diode lasers grown lattice-matched to PbTe substrates. Mesa diodes with -25 um wide stripes have been fabricated that have a wide range of single longitudinal mode emission at up to -1 mW/facet output power. These diodes have operated at up to 147 K cw, which to our knowledge is the highest cw operating temperature ever achieved with lead-chalcogenide diode lasers. The wavelength coverage of the PbTe system has so far been extended to 4.06 um cw. Longer wavelength coverage is obtained from double heterojunction diode lasers with Ma1-ySnyTe active regions lattice-matched to (Pb1-ySny)1-xYbxTe confinement layers. I n preliminary studies of diodes with x = 0.034, y = 0.14, the cw emission wavelength varied from 10.7 µm (at 10 K) to 7.1 µm (at 128 K).