A method is described in which the conventional radioallergosorbent test (RAST) for determination of allergen-specific IgE in serum has been modified by displacing the solidphase sorbent by a gel of aluminium hydroxide (Al(OH)3). The optimum conditions for this new analysis (AlRAST) are determined, taking into account speed, costs and the ratio between responses of patients and normal individuals. The AlRAST fulfills the criteria for validity: it is specific and shows parallelism between serum dilution curves. The sensitivity and reproducibility are slightly lower than in the conventional RAST, but sufficient for most routine and screening procedures. The preparation of allergosorbents in AlRAST can be accomplished within 1 h, thus making it convenient for fast screening of patients against unusual allergen extracts, as well as for allergen standardization from dose-response curves. Further, it is possible to standardize aluminium hydroxide adsorbed extracts used for immunotherapy by using the products directly as allergosorbents in the AlRAST.