“…The clinical efficacy of both extracts was dem onstrated by a num ber o f open and double-blind studies, which showed that antigen dose (4-fold) in the allergoid group. these extracts were equally effective com pared to water-based extracts, but had few er side effects [ 1,3,6,10,25,26,[29][30][31].In 1970 Marsh [12] described 'allergoids'. Allergoids are formed by the treat ment of the original m aterial with glutaraldehyde [21,22,23] and form aldehyde [2,12,15], It was shown in addition to the re duction in allergenicity and the same po tency of imm unogenicity that the m olecu lar size of the modified grass extract in creased considerably.…”