  We study hyperideal polyhedra in the 3-dimensional anti-de Sitter space
$AdS^3$, which are defined as the intersection of the projective model of
$AdS^3$ with a convex polyhedron in $RP^3$ whose vertices are all outside of
$AdS^3$ and whose edges all meet $AdS^3$. We show that hyperideal polyhedra in
$AdS^3$ are uniquely determined by their combinatorics and dihedral angles, as
well as by the induced metric on their boundary together with an additional
combinatorial data, and describe the possible dihedral angles and the possible
induced metrics on the boundary.
