House dust is one of the most common allergens that cause allergic respiratory diseases. It is a composed allergen, although the most important antigens are the mites Dermatophagoides pteronyssinus (Der p) and Dermatophagoides farinae (Der f). These mites have different geographic and climatic distribution. The aim of the study was to determine the sensitisation to Der p and Der f in our population of patients with respiratory allergic disorders. The investigation included 93 patients with perennial rhinitis and/or asthma and positive skin reactions to dust mites. Concomitant sensitisation to Der f was found in 81% of the tested patients sensitised to Der p. The same size reactions to both mites was found in 34% of patients. A larger diameter of the urtica to Der p was found in 39% of patients. In 10% a greater reaction was found to Der f than to Der p, while 3% of the subjects only had positive reaction to Der f. Patients with respiratory allergic diseases and skin sensitisation to dust mites in the investigated population were sensitised to Der p and Der f 97%:84%. In conclusion, most of our subjects were sensitised to both mites, although in some patients the correct diagnosis would not have been established if they had not been tested with Der p and Der f (in our investigation 19% of subjects). It is therefore suggested that both mites are used in the standard allergic skin prick test.