立体中心或手性中心是化合物中特殊的原子，通过交换连在该原子上两个基团的位置，就会得到原化合物的立体异构体。按照国际纯粹与应用化学联合会的定义，手性中心是“不对称碳原子”概念的拓展，它指的是连有四个不同的基团的碳原子，交换连在该原子上的两个基团的位置会得到原化合物的立体异构体。不过实际上，在有机化学中，手性中心除用于指碳原子外，也常用来指代符合条件的磷原子与硫原子。

立体中心一词是Mislow和Siegel于1984年最早使用的。

A stereocenter or stereogenic center is any point in a molecule, though not necessarily an atom, bearing groups, such that an interchanging of any two groups leads to a stereoisomer. The term stereocenter was introduced in 1984 by Mislow and Siegel. A chiral center is a stereocenter consisting of an atom holding a set of ligands (atoms or groups of atoms) in a spatial arrangement which is not superimposable on its mirror image. The concept of a chiral center generalizes the concept of an asymmetric carbon atom, i.e., a carbon atom bonded to four different entities, such that an interchanging of any two groups gives rise to an enantiomer. In organic chemistry, a chiral center usually refers to a carbon, phosphorus, or sulfur atom, though it is also possible for other atoms to be chiral centers, especially in areas of organometallic and inorganic chemistry.