AbstractA recirculation system (RS) with a single input function, heterogeneous subsystems,and a finite capacity is considered. Inside the RS the subsystems are placed in parallel and are accessed randomly.Each subsystem is considered as a GI/M/I/o single server Queueing loss system with renewal input, no waiting room, and negative exponentialIy distributed service times. The single input function is a stationary counting process.Inside the RS, at any cycle the incoming stream of units entering the system, travel inside to reach the routing mechanism. There, they are assigned upon arrival to one of the subsystems. At each subsystem,the units whicn find it full, retry to receive service oy recirculating back to the entrance of the system.There, they merge with the incoming arrival strem to form a new input to the routing mechanism at the next cycle. The units which enter each subsystem after receiving service depart from it. the previous steps are then repeated until the steady state is achieve.An open Queueing network is developed to study the asymptotic performance of the above RS. The flows of units inside the RS are approximated by a two parameter method. The performance of the RS is measured by approximating the congestion inside the RS and evaluating the efficiency of eacn of its subsystms. Finally, an example is introduced and the approximation outcomes are campared against those from a simulation study.