Objectives. To determine the level of stigma related to HIV/AIDS and its association with adherence to antiretroviral therapy (HAART). Materials and methods. A cross-sectional study that included adult patients which were part of the HAART program during at least 6 months. Stigma was defined as the loss of value of the person infected with HIV according to Berger scale and treatment adherence as the correct consume of medications which were measured with the Simplified Medication Adherence Questionnaire. Poisson regression test was used to calculate the prevalence ratios (PR) of associated factors. Results. The results of 339 surveys were analyzed. 74% were male and the median age was 39 years (Interquartile Range [IQR]: 16). High stigma was found in 25,4% of respondents, moderate in 47,5%. A reduction of 10 points in the Berger scale was associated with an increase of 5% in adherence to HAART in men (adjusted PR [aPR]: 0.95; 95% confidence interval [CI]: 0.91-0.99), and 7% in women (aPR: 0.92; 95% CI: 0.87–0.98). Conclusions. There is a high level of stigma related to HIV/AIDS and is associated with the lack of adherence to HAART according to gender. We recommend interventions aimed at reducing stigma related to status disclosure in women and related to public attitudes in men.