Abstract. Let A be a locally finite, -ގgraded, noetherian algebra with a balanced dualizing complex. If A is a Hopf algebra, then A has finite injective dimension.2000 Mathematics Subject Classification. 16E10, 16W30, 16W50.In [2] and [3] Brown and Goodearl showed that a noetherian affine polynomial identity (PI) Hopf algebra with finite injective dimension has various good homological properties. They verified that many examples of noetherian affine PI Hopf algebras, some of which are quantum groups at roots of unity, have finite injective dimension. In [2, Question A] Brown asks if every noetherian affine PI Hopf algebra has finite left and right injective dimension. Recently we gave an affirmative answer to Brown's question in [9, 0.1].In this short note we are trying to provide some evidence that a noetherian affine Hopf algebra, not necessarily PI, has finite injective dimension. We prove the following statement. THEOREM 1. Let A be a locally finite, -ގgraded, noetherian algebra with a balanced dualizing complex. If A is a Hopf algebra, then A has finite left and right injective dimension and satisfies the AS-Gorenstein condition.