In the last 5 years the Brazilian e-commerce has grown significantly, that can be proved by the increase in the number of people who shops through Internet and the growth in the volume of web sales. Parallel, the competition at virtual market is tougher and the task of conquer and keep clients has become harder. The aim of this study was to investigate how information obtained from interactions of consumers in e-commerce web sites could be used to take decisions and actions to enhance the managing of the relationship with customers. For this, a literature review was done in subjects like e-commerce and relationship with customers, especially in CRM (Customer Relationship Management) in virtual market. After that, a case study was done about one of the biggest Brazilian companies of ecommerce. The study focused into the grab process, storage, analysis and handling of customer`s information inside the company, which was described and analyzed using the literature`s conceptual pattern. The results signalized that the company`s customer information are used mainly to plan actions of sales promotion and to classify them for special offers. Some opportunities of usage in a more strategic level and aiming the tightening of this relationship with customers were identified.