Experimental results of parity violation in proton‐proton scattering are reviewed. Since the parity violation in proton‐proton scattering at 230 MeV is &rgr;‐exchange dominated, this experiment given additional independent information for the weak meson‐nucleon coupling constants. With the cooler sychrotron COSY at Ju¨lich, this aspect of weak interaction and the energy‐dependence of Azup to 2.5 GeV can be measured. Consequences for the experimental set‐up are discussed.