OBJECTIVE: A standardized method of assessing postprandial triglyceride changes is not available. We evaluated an oral triglyceride tolerance test (OTTT) designed for routine clinical and research use. RESEARCH DESIGN AND METHODS: A 200-ml strawberry-flavored test drink (50 g fat, 50 g carbohydrate) was administered twice to 30 diabetic and 20 nondiabetic subjects. Venous plasma triglyceride and glucose levels were measured when fasting and every 2 h for 8 h after the drink. Fingerprick plasma triglyceride levels were measured when fasting and at 6 and 8 h after the drink. RESULTS: The drink was consumed within 3 min and well tolerated by all subjects. The median triglyceride rise at 6 h was similar in diabetic and nondiabetic subjects (0.23 vs. 0.42 mmol/l, NS) and correlated with glucose increase at 2 h (r = 0.429, P = 0.018 and r = 0.509, P = 0.026; respectively). Diabetic subjects had higher 6-h geometric mean (1 SD range) triglyceride levels (1.82 [1.87 to 3.23] vs. 1.11 [0.66 to 1.11 mmol/l], P < 0.003) but a similar coefficient of variation (17.5 vs. 17.0%, NS) and a similar median (interquartile range) time to achieve maximal concentration (T(max)) (6.0 [4.0 to 6.0] vs. 5.0 [4.0 to 6.0] h, NS). Capillary triglyceride values were equivalent to simultaneous venous samples but consistently 10% greater. CONCLUSIONS: The OTTT permits simple evaluation of postchallenge triglyceride levels, is acceptable to subjects, and can be performed with capillary sampling. It could be used to monitor triglyceride-lowering therapies and to provide additional information concerning cardiovascular disease risk, particularly in diabetic subjects.