OBJECTIVE: Both mildly modified LDL subfraction that carries a more-negative electric charge and remnant-like particles (RLP) are closely related to triglyceride (TG) levels. We examined the relation between the RLP-cholesterol (C) level and charge-based apolipoprotein (apo) B-containing lipoprotein subfractions as determined by capillary isotachophoresis (cITP) in patients with hypercholesterolemia. METHODS AND RESULTS: cITP apo B lipoprotein subfractions were identified by analyzing plasma depleted of the related lipoproteins. While fast-migrating triglyceride-rich lipoprotein (fTRL) subfraction contained both chylomicrons and VLDL fraction, slow TRL (sTRL) only contained VLDL. cITP fLDL also contained VLDL fraction, i.e., beta-VLDL. Levels of cITP fTRL and sTRL were significantly correlated with serum levels of TG, RLP-C, apo C-II, and C-III. Levels of cITP sTRL were also correlated with apo E. Levels of cITP fLDL were positively correlated with not only LDL-C levels but also levels of TG, RLP-C, apo C-II, C-III, and E. CONCLUSION: cITP fast LDL correlated with RLP-C levels and modified the relation between RLP-C and TG levels.