In this paper the H-2-optimal control problem of systems with multiple i/o delays is presented. The problem is first converted to an equivalent H-2 regulator problem with multiple delays. The idea is to view the regulator problem in time-domain as a linear quadratic regulator problem with multiple input delays. It is shown that the rational part of the optimal controller has the same dimension as the plant and the non-rational part may be chosen to have finite impulse response. Furthermore, the regulator problem solution is also used to solve the H-2 filtering problem with multiple measurement delays. (c) 2005 Elsevier Ltd. All rights reserved.