BACKGROUND & AIMS: Postprandial lipemia is assessed using the oral fat tolerance test (OFTT), a six-hour procedure requiring hourly blood sampling. In order to simplify the test, we investigated whether a) a single postprandial triacylglycerol concentration, b) an OFTT lasting less than six hours or c) an OFTT requiring fewer blood samples, may accurately assess postprandial lipemia under various conditions. METHODS: Seventy-two subjects underwent a conventional OFTT. Predictability of single-point concentrations and time-shortened tests was assessed using linear regression and re-sampling analysis. Validity of reduced-sampling tests was assessed using Pearson's correlation coefficients and Bland-Altman analysis. RESULTS: a) A single-point triacylglycerol concentration (3 or 4h postprandially) did not present significant correlation with postprandial lipemia in the hypetriacylglycerolemic, exercise and energy restriction groups (P>0.05), b) Time-shortened OFTT (4h) was able to predict postprandial lipemia in every group studied (R(2)=0.707-0.970, P<0.01), except the hypertriacylglycerolemics (P=0.338), c) Reduced-sampling OFTT (3 or 4 samples) was able to assess postprandial lipemia in every group as well as in the overall sample (r=0.874-0.997, P<0.05). CONCLUSIONS: A more convenient, reduced-sampling OFTT may be used alternatively to the conventional OFTT, whereas a time-shortened OFTT may be appropriate only for healthy people.