Operational research (OR) has been identified as a key component of the scaling-up of antiretroviral therapy provision in resource-limited settings. OR is usually defined through its concern for applied issues and the participation of local stakeholders. Who the stakeholders should be or what their participation entails has seldom been precisely defined, and there are variations among guidelines about the conditions of their participation in the research process. The scope, achievements and limits of stakeholders' participation is analyzed here, with reference to an OR project on care practices for AIDS patients at various levels and in various sectors of the health system in Burkina Faso. The overall objectives of the project were to ameliorate care practices and to reinforce the collaboration between caregivers in non-governmental organizations, public, private, faith and community-based facilities. A large number of stakeholders was involved in the advisory committee and the research team and participated in the research from formulation to dissemination. This helped define research questions that were relevant for each sector and facilitate the acceptance of the study in the field. Some disadvantages also appeared, such as an overly broad scope of the project, delays in implementation, difficulties in coordination and unequal involvement of team members. The experience analysed here shows that effective participation of stakeholders at all stages can make a difference to the relevance, quality and implementation of OR. There may, in addition, be an optimal level of stakeholders' participation, both in terms of the numbers and composition of the group, beyond which disadvantages become apparent.