Interactive communication services as telephony and video-conferences use the infrastructure of existing LANs and the Internet more and more. The advantages are obvious. For example phone charges could be reduced significantly. But what about security? And if the communications are protected, can the quality of service be maintained? It is widely assumed that IPsec is inappropriate for the protection of real-time multimedia flows due to its not negligible computational and protocolary overhead. To address this issue we measured the performance of voice and video communications in a LAN including a wireless hop. The data transmissions over the wireless hop alternately occurred via IPsec (tunnel mode and encapsulated security payload ESP) or via plain IP. We evaluated the measurements in terms of network parameters like loss, delay, and jitter and with respect to perceived quality. In this paper we show that IPsec can be used to secure multimedia communications over a wireless link without noticeably degrading the perceived quality.