Abstract
In this paper we determine the structure of an embedded totally geodesic hypersurface F or, more generally, of a totally geodesic hypersurface F without selfintersections under arbitrarily small angles in a compact manifold M of nonpositive sectional curvature. Roughly speaking, in the case of locally irreducible M the result says that F has only finitely many ends, and each end splits isometrically as K ⨯ (0, ∞), where K is compact.