Coronary artery calcium (CAC) may encourage patients to adhere to primary prevention recommendations. This study sought to evaluate the benefit of a CAC-guided risk-management protocol in those with a family history of premature coronary artery disease (FHCAD).In this Australian multi-centre, randomized controlled trial (Coronary Artery Calcium score: Use to Guide management of Hereditary Coronary Artery Disease, CAUGHT-CAD), asymptomatic, statin-native participants at low-intermediate cardiovascular risk with FHCAD underwent CAC assessment. Those with CAC between 1 and 400 were randomized (1:1) to disclosing the CAC result to both patient and physician and commencing atorvastatin (intervention) or blinding the CAC result with risk factor education only (control). The primary endpoint of this sub-study was change in Pooled Cohort Equation (PCE) at 12 months.Of 1088 participants who were scanned, 450 were randomised and 214 in both groups completed 1-year follow-up. At 1 year, PCE-risk decreased by 1.0% (95% CI 0.13 to 1.81) in the CAC-disclosed group and increased by 0.43% (95%CI 0.11-0.75) in the CAC-blinded group. LDL-C decreased in the CAC-disclosed group in both those who continued (1.5 mmol/L; 95% CI 1.36 to 1.74) and discontinued statins (0.62 mmol/L; 95% CI 0.32 to 0.92) but was unchanged in the CAC-blinded group.Participants unblinded to their CAC showed reductions in LDL irrespective of statin continuation when compared to controls at 12 months. Improvements in individual risk factors and PCE risk were also noted. CAC assessment may positively influence patients and physicians to improve risk factor control.