Dermatophagoides farinae, D. pteronyssinus and Euroglyphus maynei were used for the investigation. The cDNA fragment coding for Der f1 and Der f2 were amplified by PCR, cloned and sequenced. By bioinformatics softwares, the amino acid sequences for Der f1 and Der f2 were deduced and compared with those for the groups 1 and 2 allergens of D. pteronyssinus and E. maynei available in GenBank. Amino acid sequence similarity analysis showed that Der p1 shared 84% identical residues with Eur m1 and 83% with Der f1. Similarly, Der p2 shared 87% identical residues with Eur m2 and 68% with Der f2. In the two phylogenetic trees constructed with group 1 and 2 allergens, D. pteronyssinus was clustered with E. maynei but not with D. farinae, although D. pteronyssinus and D. farinae belong to the same genus. D. pteronyssinus should be more similar to E. maynei than to D. farinae at evolutional level, which was not consistent with the conventional taxonomical relationship based on their morphological characteristics.