N, N'- Biisomaleimide reaets with mercuric acetate under different conditions to give vari- ous products via ring opening, addition and substitution reactions with the formation of mono- mercürated, and mercuri bis (mono-mercurated) producets. The reaction of mercuric acetate with the diazide compound (N,N'- bi -a- azidösuccinimi- de) gives mono and dimercurated azido products through N-N bond clavage.