Many parameters have a significant influence on c-commerce evolution. This complicates the assessment of the requirements for and the consequences of e-sales adoption. In order to support the decisions of companies thinking about a possible e-sales channels introduction a Decision Support System (DSS) is proposed. The relevant e-commerce success factors, which constitute the DSS input, have been identified and their influence described relying upon a literature review. The DSS output aims at describing typical e-commerce evolution patterns taking into account the speed of adoption and the steady state potential diffusion (saturation level). These variables point out the considerable discrepancies between the e-commerce evolution charactering different industrial sectors. The DSS, which is based on a system of rules, allows to qualitatively predict the expected e-sales evolution for companies introducing a specific e-sales channels strategy in a given environment and to explain it in terms of different e-commerce success factor configurations.