BackgroundThe success of the antiretroviral therapy (ART) among HIV+ persons strongly rely on individual factors, including the patient's personality characteristics [1,2], a good motivation and a set of knowledge, skills and abilities related to both the disease and treatment [3], the concurrence of adaptative emotional states [4], and a low alcohol and drugs use [5,6]. Despite convergent body of evidence has confirmed the role of individual factors on medication-adherence behaviors in Latin America countries and the Caribbean region, such as Argentina [7], Chile [8], Peru [9] and the Dominican Republic [10], little progress has been made in countries like Venezuela. In fact, only two studies using HIV+ samples have been found, in both cases putting emphasis in the influence of socio-demographic and clinical patient's characteristics on medication-adherence behaviors [11,12].Considering those antecedents and the need to investigate the influence of individual factors on medication-adherence behaviors in Venezuelan HIV+ persons, this study was justified in a psychological model for the research of adherence behaviors (PMAB) in persons living with chronic diseases, including HIV infection [13]. As show in Figure 1, the model emphasizes the interaction of psychological and biological variables along four phases. The first involves psychological process variables related to personality, motives and behavioral competencies; the second involves the HIV diagnosis and other co-morbidities; the third involves two types of behaviors: medication-adherence behaviors and disease-related behaviors -e.g., impulsivity, anger, depression, social isolation, etc.; the fourth involves biological measures and Methods: We conducted a cross-sectional study of 124 HIV+ persons recruited in an outpatient clinic in the state of Lara, Venezuela, who completed a self-administered questionnaire measuring psychological variables and medication-adherence behaviors, as well as an index of alcohol and drugs use. Moment-product correlation and structural equation modeling were applied for data analyses. Results: Current behavioral competencies showed a direct effect on medication-adherence behaviors, mediating the indirect effect of low alcohol and drugs use. The structural equation modeling demonstrated a good fit to the sample data: χ