PurposeThe purpose of this paper is to evaluate the claims made for the clinical microsystems approach of healthcare improvement within an English NHS context.Design/methodology/approachThe research adopted a Realistic Evaluation approach to examine a series of pilot clinical microsystems sites to determine what worked for whom, when and within what circumstances. Interviews and group discussions were used to collect qualitative data, whist quantitative outcome data was also collected within each of the sites. Data was triangulated to produce case studies for each of the sites.FindingsThe research concurred with many of the claims for clinical microsystems, particularly that democratic, consensual approaches to change and improvement can be better received than externally derived initiatives with imposed targets. The clinical microsystem approach emphasises identifying and nurturing strengths – of both teams and individuals – and this reinforced these positive aspects. The case study sites demonstrated higher staff morale, empowerment, commitment and clarity of purpose. To a lesser extent the research also indicated an enhanced predisposition towards improvement and innovation and a seemingly embedded sense of improvement as an ongoing (if essentially episodic) process.Research limitations/implicationsThe evaluation was limited in terms of the numbers of case study sites that it was able to incorporate. This sample represented sites of different sizes, coverage of primary, secondary and tertiary care and those reporting more and less positive experiences of the clinical microsystems approach – but any findings may be limited in their generaliseability and further studies may be needed to test out the relevance of these findings in wider settings.Practical implicationsFuture microsystem programmes will need to address components of patient involvement and process/outcome monitoring if the broader legitimacy of the approach is to be cemented and enhanced. In particular, the importance of strong data collection in achieving “high performing” status is emphasised.Originality/valueThere is currently no other empirical studies within the academic literature which investigate the value of the clinical microsystems approach to an English NHS context.