The matter of discussion is the set of states on W*-algebras. States are considered in relation to unitary mixing where the full group of unitary elements i s used. Among all the states. one could talk about. we are mainly interested in studying those the degree of mixture of which is maximally. We give a general dmcription of the set of maximally unitarily mixed states. For a finite W*algebra the set of states in question iB identified aa the set of unitarily invariant ntBtes and for oach state them is precisely one maximally mixed state com-I"trrthle with it in the s e w of unitary mixture. The latter fact fails to be true in the general c m of an infinite W'*-tllgebm. In this c w the problem is more comldicated. For a properly infinite W*-algebm we introduce an interesting syininetric ideal, the c-ideal. We prove that a state on a properly infinite W*-dgebra is mximally mixed if and only if its kernel contains the c-ideal, i. e. maximally mixed states may be identified with the set of states on the quotient algebra genemtd by the c-ideal. Por a general infinite W*-algebra the solution of the problem can be represented t w a combination of both above mentioned o m . The point of view we adopted in handling the mixture relation hw its origin in umJrAh%-'S work. *) To avoid ainhiguities (&" inea.ns v. SEuXhNN'f3 relation) we prefer to use ,,*" instead of 2) W e me 0 for denoting t.he operation of c*ent.rr-calued t.raee. UEILWAXN'I ,,> " for denoting the niirturc relation.