Cardiovascular disease (CVD) is the principal cause of mortality in chronic kidney disease (CKD) patients. Dyslipoproteinaemia is a common metabolic derangement in CKD and a traditional risk factor for CVD. This study investigates serum lipoprotein, especially small-dense low-density lipoprotein (sd-LDL), abnormalities in CKD patients. A total of 131 CKD patients (age: 59 +/- 12 years, male = 64) diagnosed according to Kidney Disease: Improving Global Outcomes, 2004 (KDIGO) and 121 age- and gender-matched control subjects (age: 58 +/- 6 years, male = 62) were recruited from Hong Kong and Macau. Serum total cholesterol (TC), triglyceride (TG), high-density lipoprotein-cholesterol (HDL-C) and direct LDL-C were assayed enzymatically. In addition, sd-LDL, together with very low density and intermediate-density lipoproteins (VLDL and IDL) were measured by US Food and Drug Administration (FDA)-approved polyacrylamide gradient gel electrophoresis. Compared to controls, CKD patients showed significantly decreased TC, LDL-C, normal-size LDL and HDL-C with increased TG, VLDL, IDL and sd-LDL (all P < 0.01). The increased sd-LDL and decreased normal-size LDL fractions resulted in a significantly elevated sd-LDL:LDL ratio in CKD (P < 0.005). In contrast to the low TC and LDL-C, sd-LDL and sd-LDL:LDL ratio were significantly elevated in CKD. Thus, sd-LDL will be used increasingly for CVD risk assessment in CKD and other diseases that show lipoprotein derangement.