This qualitative research had as its main objective, to identify factors of the nonadoption of electronic commerce within the dimension of Business-to-Consumer by the small and medium-sized companies of Puerto Rico (SMEs). An indepth interview was used, applied to six companies. The study concludes that the reasons for the non-adoption of electronic commerce by SMEs in Puerto Rico are lack of technological knowledge related to Electronic Commerce and the excessive attention to the traditional channel. The study contributes to the knowledge on the subject of the factors of the non-adoption of electronic commerce in small and medium-sized companies and provides a clearer picture of the need for them to acquire more knowledge on the subject under discussion.