A review of taxonomic treatments of the amentiferous plant taxa reveals diverse classification. It appears to be necessary to investigate new characteristics and attempt to determine the significance of these characteristics in terms of amentiferous systematics. Serological techniques have been empolyed in a systematic investigation of selected taxa of the Amentiferae: Betulaceae, Fagaceae, Juglandaceae, Myricaceae, and Salicaceae. Data by qualitative analysis of pollen proteins, double immunodiffusion and conventional immunoelectrophoresis, have proved to be valuable in delimitation of taxa tested. When the antisera against Alnus hirsuta, Betula platyphylla var. japonica, Quercus aliena, Q. dentata, Q. glauca were tested; Alnus and Betula have the greatest protein similarity to one another; and next to the rest of betulaceous genera. Relatively strong protein similarity obtained with most representatives of Quercus and Fagus when reacted with antisera against Alnus and Betula is very much in contrast to the weak protein similarity obtained for the genera of Juglandaceae, Myricaceae, particularly of Salicaceae Tested with the same antisera. When Quercus antisera were used for various genera, the weakest protein similarity was obtained with Populus.