For men with newly diagnosed prostate cancer the decisions about treatment options are complex and difficult. The aim of this study was to investigate any association between the extent to which men wanted to be involved in the decision making process, their satisfaction with that process, and their levels of decision regret after treatment. The study population consisted of men diagnosed with prostate cancer at a regional center in Australia. Men (n = 324) were invited to complete a mail out survey which included demographic questions, the treatment chosen, and three validated tools: The Control Preference Scale to measure the degree of control assumed when making decisions about medical interventions; the Treatment Decision-Making Satisfaction Scale (TDM- SAT) to assess satisfaction with the treatment decision making process; and the Decision Regret Scale to assess the level of regret after treatment. The majority of the 151 respondents (47% response rate) expressed an active decision control preference. There was no correlation between age and the treatment chosen or the degree of control men exerted over the decision-making process. Men who preferred a passive role were less satisfied with the decision-making process than were those who took an active or collaborative approach. A strong inverse correlation was demonstrated between regret experienced and satisfaction with the decision-making process. In conclusion, for men newly diagnosed with prostate cancer, taking an active role in the treatment decision making process led to greater satisfaction with that process, which in turn reduced their chances of experiencing regret following treatment.