The present work deals with the study of the effect of Admiral "pyriproxyfen" as a juvenile hormone analogue (JHA) on the protein patterns of the two common house dust mites (HDM): Dermatophagoides pteronyssinus and D. farinae.  Analysis revealed lower protein content in either JHA-treated or untreated tritonymphs than in the respective adults. JHA treatment affected protein concentration of both tritonymphs (significantly increased) and adults (significantly decreased). Significantly lower protein contents were detected for D. farinae than for D.pteronyssinus either in normal or JHA-treated individuals. A total of 49 bands with molecular weights of 10-108 Kilo Daltons (KD) and relative mobilities of 0.99-0.16 were electrophoretically separated from the whole body tissue extracts of normal and treated tritonymphs and adults of the two species. Four common bands (12-60 KD) were suggested as genus-specific. Three D. pteronyssinus proteins (21-33 KD) and one D. farinae protein (69 KD) were suggested as species- specific. The HDM allergen (14-15 KD) was detected in the two mite species. Several proteins that detected in normal individuals of the two species disappeared in the respective treated individuals that may be due to the effect of treatment with such JHA.