The aim of this study was to explore the practice of e-commerce among SMEs in Al-Qassim region, Saudi Arabia and the obstacles to e-commerce faced by managers. In order to collect the required data, a questionnaire was developed on the basis of an extensive review of the literature, and this was distributed to a sample of 100 SMEs in the Al-Qassim region. Of the distributed questionnaires, 74 completed questionnaires were returned, giving a response rate of 74%. The questionnaire comprised four main domains: the practice of e-commerce as a dependent variable while organizational, technological and environmental factors as independent variables. Each of the independent domains covered six dimensions. The results of the study supported the hypotheses that organizational factors (top management support, employee skills and experience, and business strategy alignment), technological factors (internet service quality, information technology security, perceived benefits, e-payment services, and number of technical officers), and environmental factors (customer preferences, industry characteristics, socio-cultural factors, and competitor pressure) have significant and positive relationships with the practice of ecommerce in SMEs. The absence of these factors can therefore be regarded as a barrier to the practice of e-commerce.