In this paper we apply regenerative method to estimate the required effective bandwidth (EB) of a station in an acyclic communication network. Earlier this problem for a tandem network has been addresses in [1]. We give a brief introduction to the EB theory and then discuss basic statistical methods for the EB estimation. For a queueing network described by a regenerative process we construct the estimator which gives an upper bound of predetermined QoS requirement. Simulation results show that an overestimation of a QoS parameter obtained by this method is acceptable to calculate workload-based EB for the nodes being components of highlyreliable communication systems.