For descriptor systems of the form E<(x)over dot> (t) = Ax(t) + Bu(t), y(t) = Cx(t), existing results are mostly for systems with uncertainties in the A matrix only. The case where the E matrix is perturbed renders its robust analysis quite involved and has seldom been touched by researchers. This paper will show that if E, A, B, and C are all interval matrices, the robust controllability and/or observability problems can be solved in terms of the structured singular value mu of certain fixed matrices. Necessary and sufficient conditions are given using the structured singular value mu by changing the problem into a robust nonsinylarity problem for a class of uncertain matrices.