Providing quality of service (QoS) guarantees for multimedia applications over Hybrid networks by wired and wireless LANs is rapidly becoming an important issue. In order to protect the high priority traffic flows and improve network performance in a heavy-loaded network, a new dynamic admission control algorithm is proposed in this paper. We firstly propose a method to fit the fractional autoregressive integrated moving average (FARIMA) models to four actual wireless traffic traces and a traffic prediction based on the upper probability limit. Our experiments show that the one-step forecasts based on the FARIMA models are better than those based on autoregressive integrated moving average (ARIMA) models. We also propose a prediction-based admission control algorithm in hybrid QoS networks with WiFi access using the FARIMA models. The com- prehensive simulation experiments are performed to verify the effectiveness of the pro- posed admission control algorithm.