Decision aids have been developed to help patients become involved in decision-making about their individual health care. During the evaluation of a particular decision aid in maternity care--a set of 10 'Informed Choice' leaflets--we considered the lessons learnt for evaluation of decision aids in the future. Decision aids have been tested mainly in explanatory trials and have been found to be effective. We argue that existing decision aids should be subjected to more pragmatic trials to test their effectiveness in the real world. The small amount of evidence on their use in the real world shows that they face challenges, resulting in poor implementation. Therefore, we propose that implementation strategies are developed which take heed of the findings of research on getting evidence into practice, and in particular address structural barriers such as the lack of time available to health professionals. We recommend that these 'decision aid implementation packages' are developed in conjunction with both health professionals and patients, and identify and address potential barriers to both the delivery of patient involvement in decision-making, and the use of decision aids, in the real world. These 'packages' can then be submitted to pragmatic evaluation.