The invention pertains to a method of determining a statin dosage for an individual in need of treatment with a statin, comprising determining a SLCO1B1 genotype from a nucleic acid sample of the individual, said genotype comprising the presence or absence of the SLCO1B1-056 polymorphism, and determining an ApoE genotype or phenotype identifying an ApoE polymorphism selected from the group consisting of ApoE2, ApoE3, ApoE4, and any combination thereof, wherein the combination of a SLCO1B1 genotype identifying the presence of the SLCO1B1-056 C polymorphism and the ApoE genotype or phenotype identifying one of the ApoE3/4 or ApoE4/4 genotypes indicates the statin dosage.