A note on the incentive compatible core

We identify particular exchange economies with asymmetric information in wh ich the ex ante incentive compatible core is nonempty provided that coaliti ons can allocate goods by means of random mechanisms. Both the use of rando m mechanisms and the restriction to a specific class of economies are cruci al for the result. Indeed, the ex ante incentive compatible core can be emp ty (i) in our class of economies if coalitions can only use deterministic m echanisms and (ii) outside this class, even if random mechanisms are allowe d. (C) 2001 Academic Press.