The fast adoption of IP-based communications for hand-held devices equipped with wireless interfaces is creating new challenges for the Internet evolution. Users expect flexible access to Internet based services, including not only traditional data services but also multimedia applications. This generates a new challenge for QoS provision, as it will have to deal with fast mobility of terminals being independent of the technology of the access network. Various QoS architectures have been defined, but none provides full support for guaranteed service levels for mobile hosts. This paper discusses the problems related to providing QoS to mobile hosts and identifies the existing solutions and future work needed.