Aim To study distributions and contents of high density lipoprotein(HDL) subspecies in type Ⅳ hyperlipidemic patients.Methods Apolipoprotein(apo)A_Ⅰcontents of serum HDL subspecies in 132 type Ⅳ hyperlipidemic(Ⅳ-HLP) patients and 163 normal controls were determined by two-dimensional gel electrophoresis associated with immunodection method.Results Compared with normal controls,the contents of small-sized preβ₁.-HDL,HDL_(3a) were significantly higher(p<0.01),but those of large-sized HDL_2a,HDL_2b were significantly lower (p<0.01).In addition,males had significantly higher small-sized pre β₁.-HDL,HDL_3b(p<0.05), but lower large-sized HDL_2b(p<0.01) than females in both normal controls and Ⅳ-HLP patients.Correlation between HDL subspecies and lipids in Ⅳ-HLP patients showed that triglyceride(TG) and(TG/HDLC) ratio were positively correlated with pre β₁.-HDL,HDL_(3a)(p<0.01 or p<0.05),but negatively correlated with HDL_2b,HDL_2a(p<0.01 or p<0.05).Conclusions The particle size of HDL shifted towards smaller sizes,which,in turn,indicates that reverse cholesterol transport might be weakened and HDL maturation might be abnormal.Moreover,males probably have higher pre β₁.-HDL,HDL_3b,but lower HDL_2b than females in general population.