Web Services hold the promise of a standards-based platform for automating the integration of applications over diverse networks, operating systems and programming languages. Reliable messaging is critical in this context; many enterprise systems require a messaging infrastructure that guarantees message delivery even in the presence of software and network failures. Using existing message-oriented middleware (MOM) for reliable Web services messaging seems natural. However, a variety of implementation challenges, including the support for specific reliable Web services messaging protocols, must be addressed. In this paper, we discuss the options for and implications of employing MOM to implement reliable messaging for Web services. In doing so, we contribute to the understanding of reliability for Web services in general.