. Patient and public involvement in research. Patient and public involvement (PPI) entails research being carried out 'with' members of the public, rather than 'to', 'about' or 'for' them. The word public can refer to patients, potential patients, carers and people who use health and social care services, people from organisations that represent people who use services as well as members of the public. People with lived experience of a particular service or health condition may add value to the research and even influence the research question. The involvement may occurr in any stage of the research process, but preferably since the very start, when the study is designed. To obtain a real involvement and participation some practical tips are suggested. In this paper advantages but also difficulties related to PPI are presented, based both on the literature but also from the authors' experience.