Sera of 20 patients allergic to the house dust mite Dermatophagoides pteronyssinus were investigated by crossed radioimmunoelectrophoresis (CRIE) using extracts prepared from purified mite bodies (PMB) and whole mite culture (WMC). By CRIE, different allergen patterns and different numbers of allergens were detected in the two extracts. By summarizing the values of the CRIE patterns of the 20 patients' sera into allergograms, 6 out of 16 allergens in PMB and 5 out of 10 allergens in WMC extracts could be identified as major allergens. These diverging results, together with the published literature, emphasize the necessity to reevaluate the International Standard for D. pteronyssinus.