Two boron-containing hypolipidemic agents, N,N-dimethyl-n-octadecylamine borane and tetrakis-mu-(trimethylamine-boranecarboxylato)bis-(trimethylamine- carboxyborane)-dicopper(II) were shown to reduce significantly serum cholesterol and triglyceride levels after 14 days administration in rats. Serum low density lipoprotein (LDL) cholesterol content was reduced by both agents; however, high density lipoprotein (HDL) cholesterol was elevated by N,N-dimethyl-n-octadecylamine borane but reduced by the dicopper (II) complex. The boron agents suppressed LDL binding and internalization in hepatocytes, fibroblasts and aorta cells and elevated HDL binding and degradation in hepatocytes. Enzyme activities were modulated by the boron derivatives which would favor less cholesterol deposition in peripheral tissues and further clearance from the plaque cells.