We propose an integral sliding surface for linear time-invariant implicit systems (descriptor systems). We show that, under reasonable assumptions (regularity, stabilizability) it is possible to design a stabilizing controller that compensates the matched perturbations exactly. Higher-order sliding motions are required since, for the solutions of the implicit system to be well defined, special care must be taken on the degree of smoothness of the controller and the perturbations. The algorithm is tested on a system where the perturbation enters through an algebraic equation. (C) 2013 Elsevier Ltd. All rights reserved.