Instrumented gait analysis was developed to assist in clinical decision-making to optimise treatment to improve walking in patients with complex gait problems. In this clinical lesson, two cases are presented in which instrumented gait analysis was used for a different goal. It was used to assist in finding the correct neurological or orthopaedic diagnosis in patients in whom symptoms occurred during walking. In both patients, an accurate diagnosis could not be found based on the symptoms they reported, despite a thorough analysis by the neurologist. Instead, the symptoms were caused by the compensations patients used to optimise walking and not directly by the health condition itself. Through instrumented gait analysis, the direct impact of a health condition on the gait pattern can be distinguished from compensations. It can be an asset in finding the correct diagnosis, especially in patients with complex gait problems or multiple health conditions.