INTRODUCION. Obsessive-compulsive disorder (OCD) has a high cost for families, who frequently take part in compulsions, reassure patients, assume part of their responsibilities, try to conceal the disorder, and show stigmatizing attitudes (Ociskova et al., 2013; Stengler-Wenzke et al., 2004). esTOCma is a gamified mental health mobile application (app) that offers information about OCD, suggests where to find help, and helps fight stigmatizing attitudes. The objective of this study is to test esTOCma efficacy in a sample of OCD family members. Specifically, we will analyze if, after using the app, there is a change in the following variables: mental health literacy about OCD, stigma and social distance associated with OCD, intention to seek help when having OCD. Furthermore, we will test families’ satisfaction with the app. METHOD. Participants were extracted from a total of 296 users who downloaded the app for free from Google Play Store or Apple’s App Store and identified themselves as a family member of a person diagnosed with OCD. From the initial sample, participants who used the app until completion and completed a pre- and post-intervention assessment were selected. The final sample comprised 109 participants of a mean age of 46.03 years old (SD=14.42; range 18-73), 69.7 % women. Participants completed the following measures in the app before and after the intervention: (1) mental health literacy about OCD (MHL) (7 items); (2) Attribution Questionnaire (AQ-27-E); (3) Social Distance Scale (SDS); (4) General Help-Seeking Questionnaire (GHSQ); (5) satisfaction with the app (3 items). RESULTS. On average, it took 20.61 days (SD=18.05) to complete the app. After intervention, participants showed significant changes with moderate to low effect sizes in the variables of interest. Specifically, after using the app, participants showed higher scores in mental health literacy about OCD (t (108) = -3.768, p= < .001, Cohen’s d= 0.389), lower stigma in the AQ-27-E total score (t (108) = -6.484, p= < .001, Cohen’s d= 0.50) and subscales, a lower desire for social distance (t (108) = 5.569, p= < .001, Cohen’s d= 0.618); and greater intention to seek treatment in case of OCD symptoms (t (108) = -5.194, p= < .001, Cohen’s d= 0.553). Most of them (88%) would recommend the app to a friend, appraised what they had learned using the app (96.3%) and stated that the app was very helpful (88.1%). DISCUSSION. Results show that the app is satisfactory and beneficial for family members of OCD patients as it significantly increased their knowledge about the disorder and dismissed stigmatizing beliefs about OCD. Accordingly, esTOCma could help families understand their relatives, obtain guidance to deal with their symptoms and help family members get efficacious treatment. Future studies should analyze strategies to improve the app to make it more attractive and facilitate continued use.