There is scarce information in literature about the decisions made by ethics committees concerning the clinical studies they have reviewed. A retrospective, detailed review of 666 applications, their amendments and the ethics committees' statements was undertaken. All protrocols of clinical studies on medicinal products submitted to and reviewed by the ethics committees of two university hospitals during the years 1992, 1994, 1996 and 1998 were investigated. Most of the studies were international (50%), multicenter (71%), phase III trials (41%) on a new clinical entity, (38%). Validity of the clinical drug study applications was acceptable in more than half of the cases (364; 55%), while 91 (14%) were approved with advisory comments, 153 (23%) had to be amended, 35 (5%) were left pending and 23 (3%) were rejected. Most of the questions pertained to informed consent and the study protcol. In accordance with precious results, our findings support the opinion that the submitted documents need to be improved, especially with regard to informed consent and study protocols, in order to gain better Good Clinical Practice (GCP) compliance. Well-defined, documented operating procedures of the ethics committees would have facilitated the practical issues in the review process.