Objective To report 2 families of monogenic familial hypercholesterolemia and their pedigree analysis and to improve the understanding of familial hypercholesterolemia. Methods The pedigree, biochemical results, and clinical data of 2 families of monogenic familial hypercholesterolemia were analyzed. Results There were 17 patients among 22 surviving members of two families. The onset of homozygous patients was earlier. Typical xanthoma was found among them. Their serum total cholesterol and low density lipoprotein cholesterol significantly increased. Triglycerides were normal. Electrocardiogram changes caused by the myocardial ischemia was discovered in the early stage. Conclusion The onset of this disease is early and can cause serious damages. Patients should undergo the early lipid-lowering therapy.