OBJECTIVES: Selecting conservative therapies for men with non-metastatic prostate cancer involves trade-offs between treatment attributes. An interview-based survey using conjoint analysis was undertaken to establish which treatment attributes are important to men in selecting treatments, and how attributes are traded off. METHODS: On the basis a pilot study, eight treatment-related attributes were selected for the survey: diarrhoea; hot flushes; ability to maintain an erection; breast swelling/tenderness; physical energy; sex drive; life expectancy, and out-of-pocket personal costs. A discrete choice preference elicitation mechanism was used. One hundred eighty men with non-metastatic prostate cancer from two London hospitals were invited to participate. Of these, 129 men, mean age of 70 years, 58% T-stage 1 or 2 at diagnosis, were interviewed -. Data were analyzed using random effects probit models. RESULTS: On average, men's responses to the conjoint questions were sensitive to variation in the levels of all attributes (p <0.01) and coefficient signs on all attributes were as expected. A statistically significant interaction was shown which indicated that the attribute 'ability to maintain an erection' was less important to older men (p = .001). Most men were willing to make trade-offs between avoiding side effects and both losses in life expectancy and out-of-pocket costs. In terms of the former, they were, on average, most willing to forgo life expectancy to avoid limitations in physical energy (mean of 3.01 months), and least willing to trade life expectancy to avoid hot flushes (mean of 0.58 months to move from 'moderate' to 'mild' or 'mild' to 'none'). CONCLUSIONS: Men with prostate cancer are willing and able to participate in a relatively complex exercise that weighs-up the benefits and harms of various conservative treatments for their condition, and to make trade-offs between attributes. The results provide an indication of the relative importance of different aspects of treatment to patients with prostate cancer. Cardiovascular Disease II