Many photochemical reactions are carried out under particular sustainable conditions. Often no chemical activation is necessary and the photon is considered as a traceless reagent. These reactions give access to unusual molecular structures and therefore are highly appreciated for application to organic synthesis, especially in heterocyclic chemistry. In this context, photochemical position isomerizations of heterocyclic compounds are discussed. Photochemical rearrangements induced by electron and hydrogen atom transfer (HAT) are also used for the preparation of heterocyclic compounds. Photochemical electrocyclization is discussed with sixmembered heterocycles such as pyridine derivatives. Finally, photochemically induced cyclization are presented as a very suitable method for the construction of heterocycles. The synthesis of biologically active compounds is particularly focused. Thus perspectives of sustainable chemistry are presented for the pharmaceutical and agrochemical industry.