We report the room-temperature operation of optically pumped InAs/InGaSb/InAs/AlSb type-II quantum-well lasers at 4.48 mu m with a pulse length of 650 ns and a repetition rate of 2 kHz. The absorbed threshold peak pump intensity was only 0.27 kW/cm(2) at 220 K and 1.1 kW/cm(2) at 300 K, with a characteristic temperature To of 61.6 K for temperatures up. to 300 K. At 49 K, the continuous wave output power was 4.2 mW/facet with an absorbed threshold pump power of 31.5 mW and an absorbed pump power of 62 mW, indicating a differential external quantum efficiency of 54% for two facets.