OBJECTIVES: To explore the relationship between childhood socioeconomic position (SEP) and filling of medicine prescriptions for prevention of cardiovascular diseases (CVDs), with young adult intelligence (IQ) as a potential mediator. DESIGN: Birth cohort study with logistic and Cox-proportional hazard regression analyses of associations between childhood SEP, retrieved from birth certificates, and prevalence, initiation of and refill persistency for CVD preventive medicine. SETTING: Denmark. PARTICIPANTS: 8736 Danish men born in 1953, who had no CVD at the start of follow-up in 1995, were followed in the Danish National Prescription Register for initiation of and refill persistency for antihypertensives and statins, until the end of 2007 (age 54 years). RESULTS: Low childhood SEP at age 18 was not associated with prescription fillings of antihypertensives, but was weakly associated with initiation of statins (HR = 1.19 (95% CI 1.00 to1.42)). This estimate was attenuated when IQ was entered into the model (HR=1.10 (95% CI 0.91 to 1.23)). Low childhood SEP was also associated with decreased refill persistency for statins (HR=2.23 (95% CI 1.13 to 4.40)). Thus, the HR for SEP only changed slightly (HR=2.24 (95% CI 1.11 to 4.52)) when IQ was entered into the model, but entering other covariates (education and body mass index in young adulthood and income in midlife) into the model attenuated the HR to 2.04 (95% CI 1.00 to 4.16). CONCLUSIONS: Low childhood SEP was related to more frequent initiation of and poorer refill persistency for statins. IQ in young adulthood explained most of the association between childhood SEP and initiation of statins, but had no impact on refill persistency.