The benefits of lean requirements engineering can be related to several factors. Some such as better delivery accuracy or less rework create directly tangible benefits. Others, such as customer satisfaction, are more opportunistic and become tangible in the form of lasting good customer relationships with further projects. Overall, our experience has shown that a doubling of the effort for Requirements Engineering towards10 per cent of project budget in the areas of methodology, processes, training and tool support will deliver project benefits of more than 20 percent. That's a return on investment of more than 4, even by only considering the directly measurable benefits. Enough reason that you evolve your own requirements engineering towards 'Lean'.