Background: Patients with highly increased plasma triglyceride levels are at risk of developing serious complications such as pancreatitis, coronary heart disease and stroke. Therefore it is important to rapidly decrease plasma triglyceride levels. A sufficient control of triglyceride levels with drugs like fibrates, statins or nicotinic acid can usually only be attained after a couple of weeks. Plasma exchange appears to be a fast but expensive method to reduce triglyceride levels. In this study we describe the use of a new ω–3 fatty acid and medium-chain triglyceride-rich formula diet as a therapeutic concept to reduce plasma triglyceride levels fast and effectively. Methods: Thirty-two patients with severe hypertriglyceridemia were treated with the especially composed formula diet for a period of 7 days. Results: Within this period of time, plasma triglycerides decreased from 1,601 (402–4,555) to 554 (142–2,382) mg/dl (p < 0.05). Total cholesterol levels were reduced from 417 (211–841) to 287 (165–457) mg/dl (p < 0.001). Fasting glucose and uric acid levels also slightly decreased (–8%; –12%). The formula diet as a 1-week treatment was well tolerated and accepted by the patients. Conclusion: This diet was successfully used as an acute treatment in severe hypertriglyceridemia and showed effectiveness in rapidly and safely lowering plasma triglyceride levels.