It is widely supposed that it is important to imbue patients undergoing medical procedures with a sense of hope. But why is hope so important in healthcare, if indeed it is? We examine the answers that are currently on offer and show that none do enough to properly explain the importance that is often attributed to hope in healthcare. We then identify a hitherto unrecognised reason for supposing that it is important to imbue patients undergoing significant medical procedures with hope, which draws on prospect theory, Kahneman and Tversky’s hugely influential descriptive theory about decision making in situations of risk and uncertainty. We also consider some concerns about patient consent and the potential manipulation of patients, that are raised by our account. We then consider some complications for the account raised by religious sources of hope, which are commonly drawn on by patients undergoing major healthcare procedures.