We describe some results obtained with N-MODY, a code for N-body
simulations of collisionless stellar systems in modified Newtonian dynamics (MOND). We
found that a few fundamental dynamical processes are profoundly different in MOND and in
Newtonian gravity with dark matter. In particular, violent relaxation, phase mixing and
galaxy merging take significantly longer in MOND than in Newtonian gravity, while
dynamical friction is more effective in a MOND system than in an equivalent Newtonian
system with dark matter.