Seed protein diversity as revealed by variation in SDS-PAGE has been used to reassess the taxonomic relationships between 35 species related to 24 gemera of the Brassicaceae. A total of number of 82 protein bands with molecular weight ranging between 0.064 and 0.94 were recorded in the electropherograms. These bands were used as binary characters and analyzed by the STATISCA program package using the UPGMA clustering method. The produced dendrogram from SDS-PAGE analysis showed separation of the two species of genus Raphanus at taxonomoc level of 62% wherase the remainder are separated into two groups. Also, the dendrogram showed a close affinity between genus Lepidium and genus Capsella. The phenogram shows that eight species of genus Brassica from different geographical locations are not grouped together in one cluster.