Alpha-crystallin consists of two subunits: αA- and αB- crystalline, and is a major protein component of the mammalian eye lens. Being a member of the small heat-shock protein family, alpha-crystallin possesses chaperone-like function. It prevents aggregation of partially denatured proteins and the inactivation of enzymes. Mutations in alpha-crystallin genes can cause cataract and myopathy. This review focused on some of the expression, structure, function and genetics of alpha-crystallin.