At the request of the regional authority, the system of traceability of blood products in the Midi-Pyrenees area in France was assessed using available documentation, visits and interviews of participants. We studied the time needed to obtain traceability data in the Blood Banks and the reactivity of the system defined as the time needed to carry out a simulated descending transfusional survey. This information allowed us to assess usefulness and cost of the system, its applicability and the timeliness of information, according to the criteria of the Centers for Disease Control. The system is based on a standardized nominative form for the delivery of blood products and specific feedback. For the participants, traceability makes transfusional surveys easier and improves transfusions safety. In two of the 130 hospitals, the system is linked to the "program of medicalization of information systems". In the 2nd semester of 1996, the traceability proportion was 97%. For a given date of distribution, 75% of blood products were traced in 14 days and 83% in a month. The study of reactivity showed that all donations coming from two randomly chosen blood collection sites could be traced in about 2 hours. This first evaluation of a regional system of traceability showed its feasibility and acceptability, based on evaluation criteria of a public health surveillance system. A continuous evaluation process would be necessary to assess the good functioning of the system and to detect and prevent possible deficiencies.