Enterprise information integration (EII) requires an accurate, precise and complete understanding of the disparate data sources, the needs of the information consumers, and how these map to the business concepts of the enterprise. In practice, such integration takes place in context of any enterprise information system. In the paper we explain various approaches to EII, its architectures as well as its association to enterprise application integration. We justify why XML technology contributes to finding sufficiently powerful support for EII. We present some features of the XML technology, mainly its database part, and show how it is usable in EII.