We first give an intrinsic characterization of the lambda-rings which
are representation rings of compact connected Lie groups. Then we show
that the representation ring of a compact connected Lie group G, with
its lambda-structure, determines G up to a direct factor which is a p
roduct of groups Sp(l) or SO(2l+1). This result is used to show that a
compact connected Lie group is determined by its classifying space; d
ifferent (and independent) proofs of this result have been given by Za
brodsky-Harper, Notbohm and Moller. Our technique also yields a new pr
oof of a result of Jackowski, McClure and Oliver on self-homotopy equi
valences of classifying spaces. (C) 1997 Elsevier Science B.V.