The primary objective of this study is to compare the effect of simvastatin plus Omacor to simvastatin plus placebo for lowering non-high density lipoprotein cholesterol in subjects with mixed dyslipidemia.

This trial will utilize a randomized, double-blind, two-period crossover design. At Visit 4 (Week 0), after a 5-week diet lead-in/baseline period, subjects meeting all entry criteria will be randomized to one of two double-blind treatment sequences, simvastatin/Omacor first or simvastatin/placebo first. Each treatment period consists of 6 weeks. After randomization, subjects will self-administer the study drugs once a day in the evening.

Inclusion Criteria:

• Men and women, ages 18-79 inclusive
• Fasting, untreated non-high-density lipoprotein cholesterol (non-HDL-C level above ATP III goals
• Fasting, untreated triglyceride (TG) level in the high to very high range
• Provide written informed consent and authorization for protected health information

Exclusion Criteria:

• Pregnancy
• Use of lipid-altering drugs which cannot be stopped
• History of certain cardiovascular conditions or cardiac surgery within the prior 6 months
• Body mass index above 40 kg per square meter
• Allergy or sensitivity to omega-3 fatty acids or to statin drugs
• Poorly-controlled conditions including diabetes, hypertension, or thyroid disease
• Certain muscle, liver, kidney, lung or gastrointestinal conditions
• Certain medications
• Active cancers treated within prior 2 years (except non-melanoma skin cancer)