We have followed the evolution of multi-mass star clusters containing massive central black holes by N-body simulations on the GRAPE6 computers of Tokyo University .
We find a strong cluster expansion and significant structural changes of the clusters .
Clusters with IMBHs have power-law density profiles \rho \sim r ^ { - \alpha } with slopes \alpha = 1.55 inside the influence sphere of the central black hole .
This leads to a constant density profile of bright stars in projection , which rules out the presence of intermediate mass black holes in core collapse clusters .
If the star clusters are surrounded by a tidal field , a central IMBH speeds up the destruction of the cluster until a remnant of a few hundred stars remains , which stays bound to the IMBH for a long time .
We also discuss the efficiency of different detection mechanisms for finding IMBHs in star clusters .