Abstract: We discuss the Poisson characterization of processes in M/M/1/k feedback qneueing systems and generalize the corresponding results in Bremaud 2 and 3. It turns out that the results for M/M/1/k feedback queneing systems are different from that for M/M/1 feedback queueing systems, i.e., apart from the output process, some other processes may be also Poisson under special conditions.