Objectives: To assess the predictive value of the Australian absolute cardiovascular disease risk (ACVDR) calculator and other assessment tools for identifying Australians with family histories of early onset coronary artery disease (CAD) who have coronary artery calcification. Design, setting, participants: People without known CAD were recruited at seven Australian hospitals, October 2016 – January 2019. Participants were aged 40–70 years, had a family history of early onset CAD, and a 5-year ACVDR of 2–15%. Main outcome measures: CT coronary artery calcium score greater than zero (any coronary calcification) or greater than 100 (calcification warranting lipid therapy). Results: 1059 participants were recruited; 477 (45%) had non-zero coronary artery calcium scores (median 5-year ACVDR, 4.8% [IQR, 2.9–7.6%]; median coronary artery calcium score, 41.7 [IQR, 8–124]); 582 (55%) did not (median 5-year ACVDR, 3.2% [IQR, 2.0–4.6%]). Of 151 participants with calcium scores of 100 or more, 116 (77%) were deemed to be at low cardiovascular risk by Australian guidelines, while 14 of 75 participants at intermediate risk (19%) had zero calcium scores. The sensitivity of the ACVDR calculator for identifying people with non-zero calcium scores (area under receiver operator curve [AUC], 0.674) was lower than that of the pooled cohort equation (AUC, 0.711; P < 0.001). ACVDR (10-year)- and Multi-Ethnic Study of Atherosclerosis (MESA)-predicted risk categories concurred for 511 participants (48%); classifications were concordant for 925 participants (87%) when the ACVDR was supplemented by calcium scores. Conclusions: Coronary artery calcium scoring should be considered as part of the heart health check for patients at intermediate ACVDR risk and with family histories of early onset CAD. Alternative risk calculators may better select such patients for further diagnostic testing and primary prevention therapy. Trial registration: Australian New Zealand Clinical Trials Registry, ACTRN 12614001294640; 11 December 2014 (prospective).