AbstractThe majority of people with problematic gambling behavior never seek or receive professional help. Internet-based treatment approaches have been shown to help patients overcome practical and psychological barriers associated with face-to-face therapy. In this uncontrolled pilot study, we explored the feasibility of the eight-module therapist-guided internet-based treatment program SpilleFri (“Free from Gambling”) for patients with gambling disorder (GD). We included 24 patients seeking treatment at a Danish hospital-based treatment clinic. The focus of the feasibility study was evaluation of recruitment and retention rates, data completion rates, treatment response, satisfaction, and program utility. In addition, a series of semi-structured interviews were conducted to explore patient-perceived acceptability and potential barriers to treatment completion and positive outcome. Treatment acceptability among therapists was examined in a focus group interview. Sixteen of the included patients completed the program, yielding an acceptable treatment dropout rate (29.17%), and 82.35% of treatment completers provided full data at all assessment points. Overall, patients were satisfied with the treatment received, and patient interviews highlighted multiple psychological as well as practical benefits associated with the treatment form and content. Patients with more severe gambling symptoms at baseline might be more likely to drop out before treatment completion than patients with less severe symptoms. The results suggest that SpilleFri may be a feasible alternative to face-to-face treatment for GD. However, the uncontrolled design and small sample size of the study limit the robustness of the findings. In the future, the effect of SpilleFri treatment should be examined in a randomized controlled trial.Clinical trial registrations: The study protocol was prospectively registered at clinicaltrials.gov (TRN: NCT05051085; registration date: September 21, 2021).