Impacts of the application of e-commerce on paper and energy use are analysed in a case study concerning a Dutch electronic retailer (e-tailer) of computers. The estimated use of paper associated with the e-tailer concerned was substantially reduced, if compared with physical retailing or traditional mail-order retailing. However, the overall effect of e-tailing on paper use strongly depends on customer behaviour. Some characteristics of e-commerce, as practiced by the e-tailer concerned, such as diminished floor space requirements, reduced need for personal transport and simplified logistics, improve energy efficiency compared to physical retailing. Substitution of paper information by on line information has an energy use effect that is dependent on the time of online information perusal and the extent to which downloaded information is printed. Increasing distances from producers to consumers, outsourcing, and increased use of computers, associated equipment and electronic networks are characteristics of e-commerce that may have an upward effect on energy use. In this case study, the upward effects on energy use were less than the direct energy efficiency gains. However, the indirect effects associated with increased buying power and the rebound effect on transport following from freed travel time, greatly exceeded direct energy efficiency gains.