Donor governments are prioritizing aid ‘results’ in advance of the Fourth High Level Forum on Aid Effectiveness (HFL4) in Busan, Korea, due to take place at the end of 2011. But there is a real risk that their efforts will lead to a poorly designed results policy that could undo years of work to make aid more useful for fighting poverty. In Busan, donors must focus on ensuring that aid produces the results that matter most to people living in poverty. It is crucial that they stand by the commitments they made in the Paris Declaration and the Accra Agenda for Action, and go further to ensure that aid is more effective in bringing lasting change. Evidence shows that donor efforts to measure results could in fact pose a threat to achieving this goal, as a number of donors implement results policies based on proving results and value for money to domestic constituencies.Donors must resist the temptation to prioritize results that they can count in the short-term but which will count less to poor women and men in the long-term. The risks and unintended but very real consequences of their focus on results must be taken seriously, or we will see history repeat itself. Ensuring that aid has maximum impact is a crucial step towards reducing poverty and inequality, and mutual accountability for development results is a key Paris Principle. But in order for Busan to advance a meaningful results agenda, national and international donor policy on results must prioritize the ‘right’ results.