Two Al-Ge alloys were tensile tested in the range 298 to 598 K to assess the effects of temperature, strain rate, grain size and composition on deformation in presence of precipitation. Independent of strain rate, grain size and composition, the ductility-test temperature curves went first through a maximum and then a minimum. The variations in the 0.2% yield stress, the ultimate tensile strength (UTS), the parabolic stress-strain relationship and the strain-rate sensitivity of flow were also recorded as functions of the experimental variables. Electron microscopy revealed that sub-grain formation was present from 298 K till the temperature of minimum ductility. Ge precipitation, whose size, quantity and morphology depended on the experimental conditions, was present in the temperature interval covered by the maximum and mini mum in ductility. Byond the temperature of ductility minimum, the precipitates and sub-grains were less frequently seen.