Polyenes are poly-unsaturated organic compounds that contain one or more sequences of alternating double and single carbon-carbon bonds. These double carbon-carbon bonds interact in a process known as conjugation, which results in an overall lower energy state of the molecule. Many fatty acids are polyenes, and many dyes contain linear polyenes.

There is a class of anti-fungal antibiotics which are called polyene antibiotics. Amphotericin B is one such example. Their chemical structures feature a large ring of atoms (essentially a cyclic ester ring) containing multiple conjugated carbon-carbon double bonds on one side of the ring and multiple hydroxyl groups bonded to the other side of the ring. Their structures also often have an amino-glycoside group bonded to the molecule. The series of conjugated double bonds typically absorbs strongly in the ultraviolet-visible region of the electromagnetic spectrum, often resulting in the polyene antibiotics having a yellow color.