This study assessed the satisfaction of patients receiving antiretroviral treatment (ART) in Vietnam and its multilevel predictors. Cross-sectional data were collected from January to September 2013 in eight outpatient clinics in Hanoi and Nam Dinh provinces. Patient satisfaction was evaluated using the Satisfaction with HIV/AIDS Treatment Interview Scale. Multivariable Tobit regression was utilized to measure the associations between these factors and satisfaction with treatment services. Generalized Mixed-effect Regression model was used to estimate the effect of satisfaction with the quality of service on the change between the initial and the latest CD4 cell count. Among 1133 patients, most of them were completely satisfied with the 10 domains measured (65.5% to 82.5%). "Service quality and convenience" domain which was attributed by the waiting time and administrative procedure had the lowest score of complete satisfaction. Compared to central clinics, provincial clinics were negatively associated with the overall satisfaction (Coef = -0.58; 95%CI = -0.95; -0.21). Patients rating higher score in "Consultation, explanation, and guidance of health care workers", "Responsiveness of health care workers to patients' questions and requests" and "Perceived overall satisfaction with the quality of service" were related to improvement in immunological treatment outcomes. Our results revealed the high level of satisfaction among ART patients towards HIV care and treatment services, and this had a high correlation to treatment outcomes. Interventions should focus on reducing administrative procedures, providing sufficient guidance and comprehensive services which integrate physical with psychological care for improving the health outcome of the ART program.