The purpose of this paper is to investigate empirically and identify the factors that affect the adoption of e-business in enterprise resource planning (ERP) enabled firms and non-ERP-enabled firms. To assess the determinants that influence the adoption of e-business this study develops a research model that is based on the innovation and organizational characteristics from the diffusion of innovation (DOI) theory and the environmental context from the technology-organization-environment (TOE) framework. A questionnaire-based survey was conducted in five developing countries in Western Balkan, Serbia, Croatia, Bosnia and Herzegovina, Montenegro and Former Yugoslav Republic of Macedonia (FYROM), and data from 276 firms were collected. The data were analyzed by employing factorial analysis, and the relevant hypotheses were tested by logistic regression analysis. The obtained results indicate that ERP-enabled firms and non-ERP-enabled firms with certain perceived relative advantages, top management support, government resource support and government regulatory support are more likely to adopt e-business. The obtained results offer various perspectives for (1) managers in ERP-enabled firms and non-ERP-enabled firms, (2) e-business and ERP vendors, (3) governments of five developing countries and (4) practitioners from manufacturing, distribution and service industries.