Internet-based information and communication technologies (ICTs) have offered opportunities to reconfigure supply chains. A new kind of intermediary has emerged in many industries; the cybermediary—an online intermediary that only operates in the virtual environment. Many new types of online intermediary have emerged with differing business models. As yet, there have been few attempts to describe and categorise their e-business practices or to analyse the roles that they play within their supply chains. This paper seeks to address this deficiency by addressing both the theory and practise of online intermediaries. A two-dimensional framework based on the roles of cybermediaries and their relationships between supplier and buyer in the supply chain is developed from a synthesis of the extant literature. Five roles of cybermediaries are identified: informational, transactional, assurance, logistical and customisation. Cybermediary relationships are characterised in terms of their affiliation to customers and suppliers. Case studies of three online intermediaries are presented to illustrate and test the framework. An analysis of the empirical data from these cases served to demonstrate the utility of the framework in categorising online intermediaries and offering additional understandings of the rapidly evolving world of virtual supply chains.