Objective: To study the effects of small group continuous quality improvement (CQI) on the clinical practice of midwives in the Netherlands. Design: Randomised pre-/post-test (balanced block). Intervention: The CQI groups were assigned to either the set of peer review topics including 'perineal repair' and 'artificial rupture of the membranes (ARM)', or to the set of topics including 'airway aspiration' and 'measuring blood pressure'. The two research groups acted as each other's control group. Setting: The Netherlands. Participants: Two hundred and fifty-five individual midwives practising in primary and secondary care who made up 28 peer groups. Measurement and key findings: Questionnaires were used to collect data on clinical practice prior to the start of the intervention and one year later. Pre- and post-test data were received from 156 respondents. The intervention had a positive effect on adherence to the recommendations with respect to airway aspiration of the baby and measuring blood pressure. For ARM, no difference was found between pre- and post-test adherence to recommendations in the intervention group, while in the control group, the percentage of midwives that adhered to the recommendations decreased in the period between pre- and post-test. No significant effect was found for perineal repair. Implications for practice: Small group CQI had a positive effect on changing clinical practice when the learning of new skills (e.g. learning a new suturing technique) was not necessary. Additional interventions are needed when implementing guidelines that recommend the learning of new skills. © 2003 Elsevier Ltd. All rights reserved.