Funding Acknowledgements Type of funding sources: None. Background Coronary atherosclerosis is a continuous process beginning early in life, with a long and clinically asymptomatic phase, before manifestations appear in middle and/or late adulthood. Coronary artery calcification (CAC) is a well-established marker of atherosclerosis; but the clinical validity of CAC in young adults (traditionally considered as a population group of low cardiovascular risk) remains unclear. Aim We aimed to assess the prevalence of CAC in a population of young individuals without previous history of coronary artery disease (CAD) in the UK and its association with conventional cardiovascular risk factors. Methods This analysis includes 4186 asymptomatic young individuals who underwent electron beam computed tomography (EBCT). Demographic information and the presence of cardiovascular risk factors were abstracted from referral letters and/or questionnaires completed by the patients prior to their tests. Individuals with previously documented CAD or chronic kidney disease were excluded. All EBCT CAC studies were performed using the same scanner (Imatron C300 Ultrafast computed tomography scanner, GE Healthcare, London, UK) and the same scanning protocol. Results The age (mean SD) of the study cohort was 40.5 ±3.6 years (range 26–45 years, 83.8% males). Hypertension, dyslipidemia, and diabetes mellitus (DM) were present in 15.5, 7.9, and 2.8% of individuals, respectively. Family history of premature CAD was present in 17% and 17.4% were smokers. CAC was present in 21.8% of the cohort, while individuals with CAC comparing with those with CAC score 0 were males (95.2 vs. 80%, p < 0.002), older in age (41.4 3.2 vs. 40.3 3.7 years, p < 0.0001), with DM (5.5 vs. 25%, p < 0.0001), hypertension (22 vs. 13.7%, p < 0.0001), and dyslipidemia (14.8 vs. 6%, p < 0.0001). The prevalence of CAC score 0, 1–100, 101–400, 401–1000, >1000 were 78.2, 19, 2.1, 0.5, and 0.2%, respectively. The prevalence and distribution of CAC among various age groups are shown in Table 1. CAC was found in 24.8% of males (CAC score 1–100, 101–400, 400–1000, >1000 in 21.6, 2.5, 0.5, and 0.1%, respectively) and 6.6% of females (CAC score 1–100, 101–400, 400–1000, >1000 in 5.4, 0.6, 0.15 and 0.4%, respectively) (p < 0.0001). There was no statistical difference of mean CAC score between genders (males 13.8 72.7; females 11.8 142.4; p = 0.6). In multivariate analysis, the presence of CAC was associated with age (p< 0.0001), male gender (p< 0.0001), DM (p< 0.0001), hypertension (p< 0.0001), and dyslipidemia (p< 0.0001). Conclusion In a large cohort of asymptomatic young individuals, subclinical atherosclerosis (CAC score >0) was identified in approximately 20%. Assessment of CAC score is a useful clinical tool in young individuals, as it can confirm the presence of subclinical atherosclerosis.