Even though house dust mites are one of the most important allergens, there have been few studies in China for their identification and diversity. In this study, we reported that Dermatophagoides siboney was found for the first time in Beijing, China, in a temperate zone and it was also the first reported in Asia. This survey of mite prevalence was carried out in several districts of Beijing, a city of thirty million people. House dust samples were collected from 38 homes of mite-allergic patients who visited our Allergy Department from December 2008 to January 2010. Out of 345 house dust samples collected, 64% contained mites. Dermatophagoides farinae was the predominant species in the mite population found and Dermatophagoides pteronyssinus was second, and Dermatophagoides siboney was the third. The positive rates of samples were higher in single-story homes and lower buildings. The seasonal density distribution of house dust mites showed the highest mite concentration in September through October, followed by May through July, December to next January; and lowest in March and November.