Data for the Finnish medical birth register (established 1987) are collected by local hospital personnel as a part of their routine work. The purpose of this study was to study the need of personnel for feedback and the impact of feedback on later data quality. Furthermore, we studied whether such feedback tends to modify extreme cesarean section rates. Data on attitudes towards the birth register and on the need for feedback of data providers were collected through interviews and observations. In March 1988, an information package describing births, birth procedures and infant outcomes in each hospital compared with other hospitals was sent to a random stratified sample of 26 hospitals out of a total of 53. Opinions of the package were obtained by questionnaire from 104 physicians and nurses (82% response rate). Most hospital personnel, especially physicians, had negative attitudes towards the birth register. Comparison of the hospitals which had received feedback with other hospitals in terms of quality of data furnished in 1987 and 1988 suggested that feedback may improve the technical quality of data. There was no evidence, however, that feedback caused hospitals to change their practices in regard to cesarean sections.