The action of mercuric chloride and mercuric acetate on the alkaloids quinine and cinchonine has been investigated with a view to prepare organomercury compounds. The properties and constitutions of the compounds have been studied. Mercuric chloride forms combinations with the basic nitrogen atoms of the alkaloids whereas with mercuric acetate it is posible to produce compounds by addition at the ethylenic double bond. Some of these can be conveniently employed for therapeutic purposes.