We consider genera of polyhedra (finite cell complexes) in the stable homotopy category. Namely, the genus of a polyhedron X is the class of polyhedra Y such that all localizations of Y are stably isomorphic to the corresponding localizations of X. W
e prove that Y is in the genus of X if and only if the wedge XvB is stably isomorphic to YvB, where B is the wedge of all spheres S^n such that the n-th stable homotopy group of X is not torsion. We also prove that if XvX and XvY are stably isomorphic, so are also X and Y. Several examples of calculations of genera are considered.
