In a randomized controlled trial the effect of feedback and peer review directed at the sample-taking doctor (n =179) on the sampling quality of cervical smears (n= 21,240) was studied. This paper reports the impact 6 and 12 months after the end of the intervention. Monthly feedback with peer comparison was related to a net improvement in the proportion of cervical smears without endocervical cells during the intervention period, as well as during a follow-up period lasting until 15 months after the end of the intervention. This improvement seemed to be related to a minimum of 50 or even 100 smears performed each year and was therefore not confirmed on clustered data analysis. There is a strong suggestion that the intervention also related to an increase of the number of smears showing cytological pathology, although this study lacked sufficient power to test this hypothesis.