For the purpose of epidemiological studies, epidemiologists have first to retrieve using health data patients corresponding to a defined care trajectory. This task is particularly complex because it requires the expression of temporal constraints and relationships between events. Existing approaches to achieve this are limited either in terms of expressiveness, or because of a high level of technicality unsuitable to epidemiologists. To remedy this, we propose an intuitive tool to define a care trajectory graphically and find the corresponding patients.