Isolated, small very low density lipoproteins (VLDL) from males with plasma concentrations of VLDL triglycerides ranging between 0.92 and 8.65 mmol l-1 were incubated with lipoprotein lipase. There were no differences in the size of the VLDL particles isolated from normo-respectively hypertriglyceridaemic plasmas. After incubation, 4.5 +/- 3.5% (mean +/- SD) of the initial glyceride-glycerol remained in the incubate. This amount did not vary with the plasma VLDL concentration. The incubation mixture was separated into three density fractions: VLDL, low density lipoprotein (LDL) and a high density lipoprotein (HDL) respectively. The lipid contents of these were determined. The distribution of cholesterol and phospholipids after lipolysis was highly dependent on the plasma VLDL level. The amount of cholesterol and phospholipids recovered in the LDL density region increased with the rising plasma VLDL level, the correlation coefficients for this relationship were 0.80 and 0.66, respectively. The results thus indicate that small, similar size VLDL from normo-respectively hypertriglyceridaemic plasmas have different properties.