The temperature performance of GaAs-AlGaAs vertical cavity surface emitting lasers has been studied from 60 to - 160-degrees-C. A minimum threshold current occurs considerably below room-temperature where the wavelength of the Fabry-Perot resonance of the cavity matches the wavelength of the maximum gain of the active region. The laser quantum efficiency increases for decreasing temperature, exhibiting a change of slope near the temperature of the threshold minimum.