There has been an increase in the use of social network sites as a marketing medium for commercial products and services. The aim of this paper is to examine the effectiveness of social network sites in influencing both consumer perception of quality of sports products and consumer intention to purchase sports products. A Facebook page of a fictitious brand of sports shoes was set up. The control group (n=57) was exposed to a page with only minimal information about sports shoes while the experimental group (n=59) was presented with additional information on the wall page consisting of ‘likes’ votes and positive comments about sports shoes. The findings suggest that online social influence not only can affect consumer perception of quality of a sports brand but also consumer buying intention. However, the effect that social influence has on purchase intention is limited to consumers with a low level of sports involvement and participation.