The acaricidal effects of three plant oil extracts; thyme, clove and camphor oils; against mobile stages of the two house dust mites, Dermatophagoides farinae Hughes, and D. pteronyssinus Trouessart, were examined using bioassay test. Results were compared with the lethal activity of pirimiphos-methyl as a standard acaricidal compound. After 24 h period and based on the LC₅₀ values the most toxic compound against D. farinae adult was thyme oil, followed by primiphos-methyl, clove and camphor oils. In case of D. pteronyssinus, thyme oil was also the most toxic, followed by cove  oil, pirimiphos-methyl and camphor oil. Interestingly, the larvae and males of both mite species presented a mortality rate significantly higher than females (about 2 folds) when exposed to the same concentration of oil extracts. The three plant oil extracts, particular thyme and clove oil, have potential for development as new agents for the control of the two tested dust mites.