The article concerns fidelity in relation to using mannequins in simulation-based training in social-and healthcare education. The article addresses two issues. What influences fidelity, and how does the degree of fidelity influence the students' learning processes? Simulation-based training is organized in three phases; briefing, scenario, and debriefing. The article focuses on the scenario phase. A central issue in relation to the scenario phase is fidelity; i.e. the degree to which the scenario matches the practice it is intended to simulate. The article deals with the factors that influence the students' perception of fidelity and with the impact of degree of fidelity on the students' learning processes. The empirical data include obser-views, combining observations with interviews with students and teachers in social-and healthcare colleges. The analysis shows that a high degree of fidelity simulation in the sense of employing a mannequin has advantages, such as engaging students in learning and enabling them to try out practical skills. Moreover, the degree of fidelity should be adjusted to the students' practical experiences in order to optimize their learning process. Lower degrees of fidelity may have a positive impact on developing creative thinking and reducing the students' anxiety. The implication for developing practice is that the social-and healthcare colleges employ a multifaceted approach to fidelity based on ensuring optimal learning conditions for the students. The implication for further research is to specify and systematize the interrelation of learning outcome targets, students' qualifications and the usages of different degrees of fidelity.