The electronic commerce has become a channel of advertising, commercialization and distribution of products and services, continuously increasing it¿s importance in terms of both physical and financial volumes, but still exist many gaps in the knowledge about the choice process of sales channels in the electronic commerce. The objective of this work is to raise and quantify the relevant factors in the choice of these channels in Brazil. The identification of the relevant factors was made through depth interviews with consumers, users of electronic commerce, as well as through the existing theoretical referential on the subject. The quantification of these factors was carried out with book purchasers by electronic commerce, through quantitative research, using the methodology of conjoint analysis, where the price was the most important factor, followed by delivery time, positive experience on previous purchase, usability of the site, positive recommendation of friends and the site brand. These results indicate as important attributes: price, confidence, usability and brand.