By a (right) chain ring is meant an associative ring with l whose (right) ideals are totally ordered. We first prove that a compact right chain ring is equivalent to a compact local ring whose Jacobson radical is right principal. Then, we establish that a compact right chain rings is an invariant chain ring, and must be one of the following: a Galois field, a finite proper projective Hjelmslev ring or an open rank one (classical) discrete valuation ring of a nondiscrete locally compact totally disconnected skewfield. 1991 Mathematics Subject Classification: 16A80, 16A10, 51C05. §0. Introduction A right (left) chain ring is a ring with unit whose right (left) ideals form a totally ordered set (a chain) under set inclusion. A chain ring is both a right and a left chain ring. The classical examples are the finite rings of integers modulo a power of a prime and the classical valuation rings of skewfields in the sense of Schilling [42] or more generally in the sense of Mathiak [38]. Also äs mentioned in [4], they appear äs building blocks for localization of non-commutative Dedekind rings ([21]) or of FPF-rings ([19]) äs well äs valuation domains of ordered skewfields ([43]). Moreover, such rings are also the coordinate rings of Barbilian, Klingenberg and Hjelmslev planes where two points always lie on some line. (See [1], [46], [38], [30], [3l], [27]).Compact chain rings occur äs the (open) classical discrete valuation rings of rank one in (locally compact totally disconnected) skewfields ([42]) and more recently, covertly, in the work Jo-Ann Cohen [l 1], äs certain finite projective Hjelmslev rings.