In this paper, we aim at identifying the most essential critical success factors that affect success of EC business models. Based on an extensive literature review and a panel of experts, we composed a list of success factors that were divided into prerequisites and measures of success. The list was then operationalized into a survey questionnaire that was tested with 111 representatives of leading Finnish companies involved in e-business. Most factors were confirmed to be important, while we also found some differences for respondents either valuing stability or growth in efficiency and market share. We believe that understanding business models and issues related to successfulness of different components of these models is needed before economically viable e-commerce systems can be developed.