We describe room-temperature 2.78-micrometers AlGaAsSb/InGaAsSb multi-quantum well lasers. Pulsed laser operation was observed with threshold currents of 1.1 A, a maximum power output of 95 mW, and a maximum differential quantum efficiency of 9%. Lasers operated pulsed up to 60 degree(s)C with a characteristic temperature of 58 K over the range of 0 - 40 degree(s)C. Continuous wave operation was observed up to 200 K, with a peak emission wavelength of 2.665 micrometers . To date, 2.78 micrometers is the longest emission wavelength for a room-temperature III-V laser.