Background: Although cardiovascular absolute risk (CVAR) assessment has been recommended for use in Australian general practice for a number of years, there is continuing uncertainty about its implementation and impact. Our previous work has developed a multifaceted implementation model. This study aims to investigate both the feasibility of using this model and the impact of CVAR assessment and management on general practice clinical processes and patient care. Study Design: This cluster randomized controlled trial will be conducted in general practices in Sydney, involving general practitioners (GPs), other practice staff, and patients aged 45 to 69 years without existing cardiovascular disease. Methods: A total of 32 practices (40 GPs) and 1,320 patients will be recruited. Randomization will be conducted at the practice level. The intervention group of GPs will be trained to use a CVAR implementation model, whereas the control group of GPs will continue usual care. Study outcomes include clinical processes, patient risk, use of lifestyle intervention, and prescription of antihypertensive and lipid-lowering medications. Data will be collected and analyzed using mixed methods. Study outcomes before and after the intervention will be compared, and the 2 groups will also be compared after adjusting for baseline difference and clustering factors. Discussion: This trial will be the first study in Australian general practice and one of few international studies to evaluate the impact of implementing CVAR assessment and management. Results of this study will help improve the primary prevention of cardiovascular disease and inform guidelines for clinical practice and the implementation of other health initiatives.