The microstructural and mechanical stability of Cu-6 wt. % Ag alloy obtained by cold rolling combined with intermediate heat treatments have been investigated. The stress-strain responses and fracture behavior of Cu-6 wt. % Ag alloy were examined and correlated with the microstructural change caused by thermo-mechanical treatments. The deformation bands stabilized by silver precipitates were observed in heavily rolled Cu-6 wt. % Ag alloy. The highly deformed microstructure stabilized by silver filament was observed to be unstable at temperatures above 200 degrees C. The strength of Cu-6wt.%Ag alloys were found to decrease remarkably if they were heat-treated above 300 degrees C. The fracture surfaces of Cu-Ag two phase alloys showed typical ductile type fracture. The electrical conductivity did not change appreciably up to the aging temperature of 200 degrees C and increased rapidly at temperatures above 300 degrees C. The increase of the conductivity and the decrease of the strength can be associated with the microstructural coarsening of heavily deformed linear band structure. The difference of the UTS and the conductivity between the rolling direction and the direction perpendicular to the rolling direction (on the rolling plane) were found to be relatively small.