Abstract: This document describes quality-of-service (QoS) requirements for web services. With the dispersal of web services as a business solution in enterprise application, the importance of QoS for web services is increasing rapidly to the service providers and the clients. Providers need to specify and guarantee the QoS in their web services to remain competitive and achieve the highest possible revenue from their business while the clients desire to have a good service performance in terms of very high availability, shorter response time, accuracy, etc. However, due to the dynamic and unpredictable characteristics of the web services, it is not an easy task to provide the desired QoS for web service users. Even, different web service applications with different QoS requirements will compete for network and system resources such as bandwidth and processing time. But, an enhanced QoS for a web service will bring competitive advantage for service provider. To provide such a better QoS, it is first necessary to identify all the possible QoS requirements for web services, which is the objective of this document.