This paper discusses the problem of designing stabilizing controllers for uncertain symmetric composite systems. A procedure of designing a linear (decentralized) feedback control law which will stabilize a given symmetric composite system with uncertainty is presented by using the Riccati equation approach. A feature of the procedure is that the stabilizing control law can be conducted by solving two lower-order Riccati equations (or inequalities). The uncertainties considered in the systems may be time-varying. However, the values of the uncertainties are constrained to lie within some known admissible bounds.