OBJECTIVES: The aims of this study were to (1) Estimate the relative strength of preferences for different attributes of Anti Retroviral Therapy (ART) using a stated preference discrete choice experiment (DCE) and (2) incorporate findings from qualitative research to supplement the data from the DCE. METHODS: A European study in France, Italy, Spain, Germany and the UK was undertaken with an estimated1500 PLWH designed to elicit patients’ strength of preference for different attributes of ARTs. This work presents the results from the UK and Germany. Participants were given a series of choice-style questions which presented hypothetical ARTs. Qualitative data were collected separately through individual interviews (n=48) with PLWH recruited from HIV clinics in the UK and Germany. RESULTS: In total, 549 patients participated in the DCE (249 in UK) and (300 in Germany). The results showed that a rapid improvement in CD4 count and viral load were treatment attributes valued most highly by patients (UK: OR= 0.79; CI= 0.69-0.90; P<0.001. Germany: OR=0.79; CI=0.71-0.87; P<0.001).  In addition, the absence of side effects such as diarrhoea was also valued highly (UK:OR=0.57 CI= 0.51-0.65, p<0.001. Germany: OR=0.79, CI=0.72-0.86; P<0.001), as well as lower risk of long- term toxicities such as decline in renal function and an increase of cardiovascular risk (UK: OR= 0.30 CI= 0.25-0.35, p<0.001. Germany: OR=0.55, CI=0.48-0.63, p<0.001). Other treatment attributes driving patient preference included reduction in treatment failure, absence of food restrictions with ART, and fewer drug-drug interactions (DDIs). The main difference between the German and UK results is that German patients did not value the absence of DDIs, the qualitative data suggests that they felt that these issues are being managed by their clinician. CONCLUSIONS: The DCE demonstrated that patients placed a great deal of importance on treatment efficacy as evidenced by the importance placed on these attributes.