LDL receptor gene expression promoters containing a 1,2,4-triazine derivative of the formula (I): ##STR1## wherein R.sup.1 is optionally substituted phenyl or heterocycle; R.sup.2 is optionally substituted phenyl, naphthyl, aralkyl, 5- or 6-membered aromatic heterocycle, alkyl, or alkenyl; X is O, S or NR.sup.4 ; R.sup.3 is optionally substituted phenyl, naphthyl, aralkyl, 5- to 6-membered aromatic heterocycle, alkyl, cycloalkyl or alkenyl, provided that when X is NR.sup.4, then it may form an optionally substituted nitrogen-containing heterocycle, or a pharmaceutically acceptable salt thereof, which can increase the expression dose (the amount of mRNA) of LDL receptor gene, and thus increase the amount of LDL receptor, and reduce the serum cholesterol level, and are useful in the treatment of hyperlipidemia.