It is well recognized that most medications exhibit wide interindividual variability in their efficacy and toxicity. These differences may be due to genetic factors affecting the metabolism and action of these drugs, as well as to environmental factors. Genetic polymorphisms (SNPs and haplotypes) that may play a role in the differences in response to lipid lowering therapy have recently been identified, including genetic variants of apoproteins (apo AI, apo E, apo B), several enzymes (lipoprotein lipase, lecithin cholesterol acyl transferase, hepatic lipase), membrane transporters (ABCA1, ABCG5/8), and receptors (LDL cholesterol receptor). Clinical studies analysing relations between these genetic variants and the response to hypolipemiant drugs are exposed in this review.