ABSTRACT Objective: to evaluate the effect of music therapy on the stress of chemically dependent people. Method: quasi-experimental study conducted at a philanthropic institution with 18 chemically dependent people undergoing treatment. Salivary cortisol (stress hormone) was collected in three moments: before, 60 minutes after, and 120 minutes after a music therapy group intervention. Statistical analysis adopted a significance level of p < 0.05 and used the Wilcoxon and Kruskal-Wallis non-parametric tests. Results: after 60 minutes of intervention, there was a statistically significant reduction in mean salivary cortisol levels (p < 0.001). A reduction was also noted after 120 minutes, but without statistical significance (p = 0.139). Conclusion: a single session of 60 minutes of group music therapy was able to reduce stress (salivary cortisol levels) of chemically dependent people.