Simultaneous amplification of the promoter and 17 (out of 18) exons of the LDL-R gene (along with flanking intron sequences) was performed in 36 patients with hypercholesterolemia and early-onset coronary artery disease. The identification of the PCR-products on denaturing gradient gel electrophoresis (DGGE) revealed 34 cases of heteroduplexes in 24 patients. The heteroduplexes in exons 12, 10, and 2 (31%, 28% and 22%, respectively) probably reflect common polymorphism of LDL-R gene, while heteroduplexes in exons 6, 4 and 13 are less frequent (5.6%, 5.6%, and 2.8%, respectively). Significant association between the genetic variants, or polymorphism with clinical manifestations, could not be established.