The evaluation of health actions requires large amounts of information allowing an assessment of relevance, coherence, efficacy, efficiency and impact of these interventions. Information systems should support evaluation processes by helping to obtain pertinent indicators, tracers and standard operating procedures. To reach this objective, specific functions need to be implemented, including traceability, documentation, investigation and scientific awareness. But this supposes that health information systems respect quality criteria that this article defines. The following criteria are considered: simplicity, validity, acceptability, informative value, representativeness, continuity, reactivity, fluidity, flexibility of the system, and also confidentiality of information. The historical developments of medical informatics have induced the creation of independent information systems, answering to specific objectives. This lack of integration is an obstacle to the evaluation of health actions because of the difficulty to view transversally and longitudinally the sequence of actions for a same patient. Thus integrated health information systems, organised around patient care episodes, are necessary to support evaluation and to contribute effectively to decision making in public health, because the evaluation of health actions implies the availability of information about the individuals who are the targets of these actions.