Patient and public involvement in health care is important, but the existing definitions of the concept do not integrate the stakeholders' own perceptions.To investigate and compare service users' and service providers' own definitions of patient and public involvement and their implications.Qualitative study with mainly individual in-depth semi-structured interviews conducted between June 2007 and June 2009. Data were analysed using a grounded theory approach.A total of 20 patients, 13 public representatives and 44 health service providers/managers in both somatic and mental health care were interviewed. A common definition of patient and public involvement emerged: It is founded on mutual respect, carried out through dialogue aiming at achieving shared decision making. Nevertheless, users and providers assigned different values to the core aspects: Respect was imperative for service users and implied for providers, dialogue was a way to gain respect for service users and to achieve good outcome for providers, and both worried that the other party wanted to make sole decisions.Users and providers need to consider that although they have a common definition of involvement in health care, they assign different values to its aspects. Increasing and improving patient and public involvement therefore requires knowledge on and dialogue between the parties about these differences.