Low density lipoprotein receptor(LDLR) mRNA in peripheral blood mononuclear cells(PBMC) belong to low abundance expression and is difficult to detect.This study found that using the reverse transcription(RT)-polymerase chain reaction(PCR)procedure for semiquantitative determinating expression levels of LDLR gene is a highly sensitive and specific,and gives a convinient and necessary method for clinical studying expression levels of LDLR gene in PBMC from patients with hypercholesterolemia and coronary heart disease.