BACKGROUND Current allergy diagnosis is performed with allergen extracts which contain a variety of allergenic and nonallergenic components. The availability of highly purified and well-characterized allergen molecules seems to be an advantage of component-based diagnosis. METHODS With the immunoenzymatic CAP FEIA System, we measured specific IgE levels to the recombinant allergens rPhl p 1, rPhl p 2, rPhl p 5, rPhl p 6, rPhl p 7, rPhl p 11, rPhl p 12, and native Phl p 4 in 77 sera of patients allergic to grass pollen, in order to evaluate the IgE-binding frequency to these purified grass-pollen allergens and their relationship to rBet v 4, rBet v 2, and other allergens. RESULTS The frequency of sensitization was as follows: rPhl p 1=93.5%; rPhl p 2=67.5%; rPhl p 5=72.7%; rPhl p 6=68.8%; rPhl p 7=7.8%; rPhl p 11=53.2%; rPhl p 12=35.1%; and native Phl p 4=88.3%. As expected, rPhl p 7 and rPhl p 12 had a very good correlation (Spearman's r) with Bet v 4 (r=0.95%, P<0.05) and rBet v 2 (r=0.99, P<0.05), respectively. Good correlations of rPhl p 12 with papain (r=0.93, P<0.05), latex (r=0.92, P<0.05), and bromelain (r=0.86, P<0.05) were found. Highly variable individual sensitization patterns were observed. CONCLUSIONS A new clinical approach has allowed the determination of specific allergograms for the different patients and may therefore be of great importance for more specific diagnosis. The use of component-resolved diagnostics may be useful to evaluate the allergen content of an extract for immunotherapy by monitoring patient's IgE and IgG directed to relevant allergens.