We implemented a parallel Swendsen–Wang algorithm for a 2D Ising system without magnetization in a host–node programming model. The simulations were performed on the Intel Hypercube IPSC/860. Our maximum number of updates/s on 32 nodes ist three times as high as in the implementation by Stauffer and Kertész on the same machine. With 32 processors we reach half the speed of the simulations by Tamayo and Flanigan on 256 nodes of a CM5. We discuss the non–equilibrium relaxation for the energy and the magnetization.