Within the context of a quality initiative for a clinical research unit, participants' opinions relative to participation conditions allows the identification and quantification of certain dysfunctions in the unit or more widely of the site. An initial satisfaction survey of users of the Grenoble Clinical Research Center showed that the management of volunteers by a staff dedicated to, and in an environment adapted to, clinical research protocols is associated with elevated participant satisfaction. Corrective action has been taken relative to points of dissatisfaction. We conducted a second participant survey from June 1st, 2004, to May 31st, 2005, to measure the impact of our corrective actions. Eighty five percent of the persons contacted responded, and 90.4% of completed questionnaires were valid. The global satisfaction level on a scale of ten was 8.53 +/- 1.16 in 2005 (n = 292) versus 8.61 +/- 1.16 in 2004 (n = 144) (Not Significant = NS). Scores for each dimension of care (comprising 1-6 questions each) were not statistically different between the two years. An improvement was noted for the frequency of physician visits, the communication of results, and the explication of aftercare. On the other hand, there was a moderate decline of the satisfaction score relative to concern for personal needs, the swiftness of check in at arrival and the unit's peace and quiet. Globally, the participation of a subject in clinical research in the context of a Clinical Research Center is associated with a high satisfaction score. Nevertheless, the practice of annual satisfaction surveys permits the sensitisation of staff to certain specifics points, and to observe the effect of corrective action. It serves as an important element in the context of a quality initiative.