[en] An immunoradiometic assay for immunoglobulin E (IgE) using high adsorption polystyrene test tubes as the solid phase (the 'Maxisorp' assay) is described. The sensitivity of the method was found to be 50 pg IgE/ml and the within-assay reproducibility was 3-7%. The accuracy was estimated by means of a comparison between the Maxisorp assay and paper radioimmunosorbent test and a correlation coefficient of 0.98 (P < 0.001) was obtained. The authors conclude that the Maxisorp assay is a fast and reliable assay for IgE determination in cord blood, cell culture supernatants and other highly diluted IgE preparations. (Auth.)