We deal with the design of robust controllers for linear time invariant uncertain singularly perturbed systems using Periodic Output Feedback. The singularly perturbed uncertain system is represented using interval matrix representation. The fast and slow subsystems are obtained using interval arithmetic. The fast modes are assumed to be stable. The periodic output feedback gain is obtained for slow subsystem. The reduced control obtained from the slow subsystem is shown to stabilize the original uncertain system. A numerical example illustrates the proposed method. © 2006 IEEE.