At the dawn of the Digital Economy, companies are facing with dematerialization and digitization of products and the trend towards service delivery. By supporting specialization and modularization of service providers, cloud computing involves the trend towards distributed service generation. Hence, multi-vendor networks arise and IT departments have to handle heterogeneous IT Service Value Networks (ITSVN). This research paper analyzes the concept of heterogeneity in ITSVN. Based on a literature review, this paper introduces a model of heterogeneity in ITSVN. Elements of this model are applications, platforms, infrastructures, actors, technologies, interfaces, and tools. Heterogeneity is caused by the diversity and alterity of the attributes of these elements. This article offers a fundamental understanding of the effects of heterogeneity in ITSVN, a definition of heterogeneity in ITSVN, and a model of influencing factors on heterogeneity in ITSVN.