The acricidal potency of some essential oils can be applied to the control of house dust mites. But it is more effective keeping the house dust mites away than killing them because they remain as allergens even after death. The most efficient repellent concentration of lavender and tea tree in 10㎕ against house dust mites (Dermatophagoides farinae and D. pteronyssinus) were experimented by direct contact bioassay method at various doses ; 2.5, 1.25, 0.625, and 0.3125% and at vairous exposure times ; 15, 30, 60, 120, and 180 minutes. The most effective dose of essential oils (lavender and tea tree) against house dust were 0.625% and the repellent effectiveness at the mowt effective dose of 0.625% were 95.6% for lavander and 96.2% for tea tree, respectively. These results suggest that lavender and tee tree can be effectively used in the control of house dust mites.