This paper relates the reliability properties exhibited by SiGe HBT devices. Different type of stress have been applied (DC life test, hot electron stress and radiation experiments). It has been shown that hot electron stress turns out to a surface degradation confirmed by noise measurements, RF measurements and physical simulations. Concerning the radiation experiments, the results have shown that a degradation mechanism is located at the surface attributed to mobile charges in the passivation layer. Finally, it is stated that SiGe devices feature attractive reliability properties and that they could be used in space applications. (C) 2003 Elsevier B.V. All rights reserved.