Porphine or porphin is an organic compound of empirical formula C₂₀H₁₄N₄. It is heterocyclic and aromatic. The molecule is a flat macrocycle, consisting of four pyrrole-like rings joined by four methine bridges, which makes it the simplest of the tetrapyrroles.

The nonpolar tetrapyrrolic ring structure of porphine means it is poorly soluble in most organic solvents and hardly water soluble. As a result, porphine is mostly of theoretical interest. It has been detected in GC-MS of certain fractions of Piper betle.

Substituted derivatives of porphine are called porphyrins. Many porphyrins are found in nature with the dominant example being protoporphyrin IX. Many synthetic porphyrins are also known, including octaethylporphyrin and tetraphenylporphyrin.