The rapid growth of the electronic commerce (EC) sector saw the traditional business models of many large organizations being challenged by internet technology-based dot.com start-ups. One reason that can be identified for this is the inability of the information technology (IT) units of these large organizations to respond in a timely manner to the technological innovation and entrepreneurial challenge of electronic commerce. There is therefore a need for chief information officers (CIOs) and information systems managers in large organizations to pay greater attention to nurturing electronic commerce ìintrapreneurshipî (also known as corporate entrepreneurship) within their IT units. This study develops and empirically validates a theoretical model for electronic commerce intrapreneurship within the IT units of large organizations through an empirical survey of chief information officers. The survey focuses on measuring the level of EC intrapreneurship within the IT unit as represented by its four theoretical components: new business venturing, innovativeness, self- renewal and proactiveness. The study also investigates other constructs representing the environmental and organizational antecedents of IT unit intrapreneurship, as well as its effects on both electronic commerce assimilation and organizational performance. The results clarify the role that the IT units of large corporations have played in the organizational response to the business and technical innovation challenge of electronic commerce.