Amidines, structural units of a large number of biologically active molecules (antiparasitic, antidiabetic, anti-cancer, anti-inflammatory, anti-malarial,...), many compounds of biological interest, bioactive natural products and certain drugs, constitute synthons useful in organic synthesis. They are important intermediates for the synthesis of many nitrogenous heterocyclic compounds (pyridines, pyrimidines, benzimidazoles, ... and 1,2,4-triazoles). The multiple methods for obtaining amidines from various nitrogen compounds, and their use in organic synthesis and in therapeutics are described in this bibliographic review.