Aims: Acute coronary syndromes (ACS) are often caused by rupture of non-flow limiting "vulnerable" atherosclerotic plaque, characterised by a large necrotic core pool and a thin, inflamed fibrous cap that are unidentifiable with diagnostic coronary angiography. The implementation of novel invasive imaging modalities, such as intravascular ultrasound-virtual histology (IVUS-VH) and near-infrared spectroscopy (NIRS), could help identify high-risk patients who are in need of aggressive medical therapy. The intake of high dose rosuvastatin has been shown to reduce plaque containing necrotic core in the carotid arteries, however it remains unknown whether there is a similar effect in the coronary arteries. Methods and results: The IBIS-3 study is a single centre, non-randomised study designed to evaluate the ability of 12-months high dose rosuvastatin treatment (40 mg daily po) to reduce the necrotic core of a non-intervened coronary segment assessed with IVUS-VH. All patients undergoing diagnostic angiography or percutaneous coronary intervention (PCI) are eligible for participation. Recruitment started in early 2010 and will continue until 350 patients are included. The effect on the lipid core Conclusions: IBIS-3 will assess the efficacy of high dose rosuvastatin to reduce the necrotic core in a coronary segment of patients who have undergone diagnostic angiography or PCI.