This book covers various aspects of the synthesis of multisubstituted hydrazines. It includes both the review on the modern methods of the synthesis of multisubstituted hydrazines and also the results of the studies obtained by the author. The literature overview covers synthesis of mono- and disubstituted hydrazines, Ullmann renessaince in the copper-catalyzed arylation and use of azo compounds. Finally, a new methodology for the synthesis of substituted hydrazines is introduced. The first part of the experimental studies was devoted to design, synthesis and use of the new hydrazine precursor for the introduction of various alkyl- and acyl groups. In the second part the above-mentioned precursor was used in the preparation of several multisubstituted hydrazines. These compounds were studied in respect to the copper-catalyzed arylation. In the third part of the studies an unusually regiospecific nucleophilic addition to the unsymmetrical azo compounds was found. Copper catalysis was combined with azo compounds and the outcome was the discovery of two new reactions.