OBJECTIVE To create an inclusive and accurate registry of all percutaneous coronary intervention (PCI) procedures performed in the UK for audit to assess quality of care, drive improvements in this care and to provide data for research. METHODS Feedback to PCI centres with 'live' online data analysis and structured monthly and quarterly reports of PCI activity, including process of care measures and assessment of risk-adjusted outcome. Annual national reports focused on the structure of the provision of PCI across the UK, the appropriateness and process of its delivery and outcomes. METHODS All hospitals performing PCI in the UK. 1994 to present. METHODS Consecutive patients treated by PCI. Approximately 80,000 new procedures each year in recent years. METHODS All attempts to perform a PCI procedure. This is defined as when any coronary device is used to approach, probe or cross one or more coronary lesions, with the intention of performing a coronary intervention. METHODS 113 variables defining patient demographic features, indications for PCI, procedural details and outcomes up to time of hospital discharge. METHODS Data entry into local software systems by caregivers and data clerks, with subsequent encryption and internet transfer to central data servers. METHODS Local validation, range checks and consistency assessments during upload. No external validation. Feedback of data completeness to all units. BACKGROUND Available for research by application to British Cardiovascular Intervention Society using a data sharing agreement which can be obtained at http://www.bcis.org.uk.