The present research addresses the issue of source credibility of social media influencers from the perspective of users. Social media influencers are defined as online personalities with a large number of followers, across one or several social media platforms. They have a complex role, being content creators, online opinion leaders, and even entrepreneurs. Influencer marketing is becoming a more and more relevant component of current advertising campaigns worldwide. A consistent body of literature has underlined the importance of source credibility for the effectiveness of advertising. Recent researches on Source Credibility Theory (Teng et al, 2014; Djafarova & Rushworth, 2016; Munnukka et al 2016; Lou &Yuan, 2018) have stressed the influence of trustworthiness, expertise, similarity and attractiveness as elements of source credibility on perceived trust in influencer marketing. In order to gain better insights, we chose to conduct qualitative research that can allow us an in-depth perspective on the phenomenon of source credibility in influencer marketing. We carried out four group discussions in Germany and five in Romania. We explored the differences and similarities regarding the users’ perception of the perceived credibility of social media influencers.