Hydrazine, hydrazone and hydrazide derivatives are nitrogen-nitrogen bond containing compounds. Such molecules are relatively scarce in nature and have been isolated from plants, marine organisms and microorganisms. These compounds exhibit remarkable structural diversity and relevant biological activities. The enzymes involved in the formation of the N-N bond are still unknown, but many lines of evidence support the involvement of N-nitrosation and N-hydroxylation activating steps. Beside the challenging N-N bond, N-acylases catalyzing the C-N bond formation contribute to the chemical diversity of N-N-containing natural products (N2NP). This review examines the state of knowledge regarding the biosynthesis of N2NP, for which only two biosynthetic gene clusters have been investigated. Biological properties and chemical synthesis of hydrazines, hydrazones and hydrazides are also reported.