The aim of this study was to determine whether the atherogenic index of plasma (AIP=log [triglycerides/HDL-cholesterol]) differs in heterozygous familial hypercholesterolemia (FH) patients with and without a history of cardiovascular disease (CVD). Design and methods: A total of 555 FH patients with known mutations in the LDL receptor or the apolipoprotein B gene, of whom 53 had a history of CVD (CVD+ group), were retrospectively analyzed. Results: Compared to patients without CVD (CVD- group), CVD+ patients showed significantly higher fasting LDL-cholesterol, triglycerides and AIP as well as lower HDL-cholesterol. After both adjustment for age and diabetes and using analysis based on age and sex matched groups, only the increase in triglycerides and AIP in the CVD+ vs. the CVD- group remained significant. Conclusion: The results of the present study indicate that AIP, which reflects the presence of atherogenic small LDL and small HDL particles, may be connected to the risk of CVD in FH patients.