Effects of Vytorin Versus Placebo in Subjects With Primary Hypercholesterolemia (Study P04420)

Inclusion Criteria: * Subjects must be \>=18 years and \<=75 years of age, male or female. * Primary hypercholesterolemic subject with a plasma LDL cholesterol concentration \>3.64 mmol/L (140 mg/dL) to \<=6.3 mmol/L (250 mg/dL) using the Friedewald calculation; total cholesterol (TC) \>5.2 mmol/L (200 mg/dL) to \<12.7 mmol/L (500 mg/dL) and triglyceride concentrations of \<=3.99 mmol/L (350 mg/dL) should be met at the same time. At the time of recruitment (Visit 1), these values may be lower if the subject is on lipid-lowering therapy. (ie, prior to the start of lipid lowering drug washout) or may be higher at the start of dietary therapy. * Liver transaminases (ALT, AST) \<=50% above the upper limit of normal, with no active liver disease and CK \<=50% above the upper limit of normal. * Clinical laboratory tests (complete blood count \[CBC\], blood chemistries, urinalysis) must be within normal limits, or clinically acceptable to the investigator/sponsor. * Women of childbearing potential (includes women who are less than 1 year postmenopausal and women who become sexually active) must be using an acceptable method of birth control. * Subjects must be free of any clinically significant diseases other than hyperlipidemia that would interfere with study evaluations. * Subjects must understand and be able to adhere to the dosing and visit schedules. * Subject must agree to remain on a cholesterol-lowering diet for the duration of the study (according to China Adult Treatment Panel of High Blood Cholesterol). Exclusion Criteria: * Subjects whose body mass index (BMI=weight \[kg\]/height2 \[m\]) is \>=30 kg/m2 at Visit 3 (Baseline Visit). * Subjects who have known hypersensitivity to HMG CoA reductase inhibitors. * Subjects who consume \>14 alcoholic drinks per week. (A drink is: a can of beer, glass of wine, or single measure of spirits). * Any condition or situation, which in the opinion of the investigator, might pose a risk to the subject or interfere with participation in the study. * Women who are pregnant or nursing. * Subjects who have not observed the designated washout periods for any of the prohibited medications. * Congestive heart failure defined by NYHA as Class III or IV. * Uncontrolled cardiac arrhythmia. * Myocardial infarction, coronary bypass surgery, or angioplasty within 6 months of study entry. * Unstable or severe peripheral artery disease within 3 months of study entry. * Unstable angina pectoris within 6 months of study entry. * Uncontrolled hypertension (treated or untreated) with systolic blood pressure \>160 mm Hg or diastolic \>100 mm Hg at study entry. * Uncontrolled (as determined by fasting glucose \>180 mg/mL or HbA1c \>9%) or newly diagnosed (within 1 month of study entry) diabetes mellitus. * Uncontrolled endocrine or metabolic disease known to influence serum lipids or lipoproteins, ie, secondary causes of hyperlipidemia, such as secondary hypercholesterolemia due to hypothyroidism (thyroid stimulating hormone \[TSH\] above upper limit of normal). Subjects with a history of hypothyroidism who are on a stable therapy of thyroid hormone replacement for at least 6 weeks are eligible for enrollment if TSH levels are within normal limits before enrollment. * Known impaired renal function (plasma creatinine \>2.0 mg/dL), or nephrotic syndrome at study entry. * Disorders of the hematologic, digestive, or central nervous systems, including cerebrovascular disease and degenerative disease that would limit study evaluation or participation. * Known HIV positive. * Cancer within the past 5 years (except for successfully treated basal and squamous cell carcinomas). * History of mental instability, drug/alcohol abuse within the past 5 years, or major psychiatric illness not adequately controlled and stable on pharmacotherapy. * Female subject receiving hormonal therapy, including hormone replacement, any estrogen antagonist/agonist, or oral contraceptives.