To explore the decisional process of people living with human immunodeficiency virus (HIV) currently enrolled in antiretroviral clinical trials.Cross-sectional retrospective study. Outcome variables were reasons to participate, perceived decisional role (Control Preference Scale), the Decisional Conflict Scale and the Decisional Regret Scale. Descriptive statistics were calculated, and associations among these variables and with sociodemographic and clinical characteristics were analyzed with non-parametric techniques.Main reasons to participate were gratitude towards Fundación Huesped (47%), the doctor's recommendation (32%), and perceived difficulty to access treatment in a public hospital (28%). Most patients thought that they made their decision alone (54.8%) or collaboratively with the physician (43%). Decisional conflict was low, with only some conflict in the support subscale (median=16.67). Education was the only significant correlate of the total decisional conflict score (higher in less educated patients; p=0.018), whereas education, recent diagnosis, living alone, lower age, being man and doctor's recommendation to go to Fundación Huésped related to higher conflict in different subscales. Nobody regretted to participate.The decision making regarding participation in HIV trials, from the perspective of participants, was made respecting their autonomy and with very low decisional conflict. Currently, patients show no signs of regret. However, even in this favorable context, results highlight the necessity of enhancing the decision support in more vulnerable patients (e.g., less educated, recently diagnosed or with less social support), thus warranting equity in the quality of the decision making process.