ABSTRACT Research question: The proliferation of marketing stimuli to gamble on sports is a growing concern in many jurisdictions. However, little is known about the perceived influence of marketing among the most severe group of problem gamblers (i.e. those receiving treatment). This study aims to explore how problem sports bettors perceive gambling marketing is affecting them. Research methods: It examines the opinions of 43 sports bettors undergoing treatment for gambling disorder. Seven qualitative focus groups were carried out to understand their self-reported views on gambling marketing influence. Responses were analysed using a thematic analysis approach. Results and findings: The results showed three main marketing paths for impact: (i) mass-mediated marketing stimuli, (ii) personalised marketing, and (iii) stimuli inside betting shops. Price-related promotions (e.g. bonuses) were viewed as especially harmful. Also, the use of cognitive biases by bookmakers made it harder for sports bettors to stop gambling, and constantly facilitated their relapse. Implications: The paper provides evidence to substantiate regulatory action to restrict gambling promotions. In addition, it recommends that gambling companies develop responsible gambling measures to reduce the cognitive biases ingrained in their sports betting products.