Objectives An increase in the number of CT investigations will likely result in a an increase in unrequested information. Clinical relevance of these findings is unknown. This is the first follow-up study to investigate the prognostic relevance of subclinical coronary (CAC) and aortic calcification (TAC) as contained in routine diagnostic chest CT in a clinical care population. Methods The follow-up of 10,410 subjects (>40 years) from a multicentre, clinical care-based cohort of patients included 240 fatal to 275 non-fatal cardiovascular disease (CVD) events (mean follow-up 17.8 months). Patients with a history of CVD were excluded. Coronary (0–12) and aortic calcification (0–8) were semi-quantitatively scored. We used Cox proportional-hazard models to compute hazard ratios to predict CVD events. Results CAC and TAC were significantly and independently predictive of CVD events. Compared with subjects with no calcium, the adjusted risk of a CVD event was 3.7 times higher (95% CI, 2.7–5.2) among patients with severe coronary calcification (CAC score ≥6) and 2.7 times higher (95% CI, 2.0–3.7) among patients with severe aortic calcification (TAC score ≥5). Conclusions Subclinical vascular calcification on CT is a strong predictor of incident CVD events in a routine clinical care population.