Adherence to antiretroviral (ARV) treatment during adolescence and young adulthood is a significant clinical issue for the current management of the HIV/AIDS epidemic in Romania. Understanding patients' own perceptions of their adherence behaviours and related psychological barriers is instrumental for developing robust interventions, and developing psychometrically sound instruments is essential for measuring adherence in this population. We adapted to Romanian an internationally validated questionnaire for the evaluation of ARV treatment adherence. We subsequently conducted a cross-sectional survey to examine its psychometric properties and investigate the relations between self-reported aspects of adherence and established indicators of adherence and health status: Pill count, doctor's assessment of patient's adherence and viral load. Results suggest that low self-reported adherence is particularly associated with experiencing side effects and emotional distress, as well as perceptions of high treatment difficulty and time demands, low self-efficacy, low treatment efficacy and low treatment satisfaction. Perceptions of improvements in health status were overall associated with increased adherence, but feeling good physically sometimes preceded non-adherence behaviours. The questionnaire proved psychometrically sound according to classical test theory criteria (e.g. Cronbach's α = 0.77, significant associations with adherence and health status indicators). Addressing adherence barriers in clinical practice with this population may help reduce their potential impact on behaviours.