The present work deals with application of seed protein diversity as revealed by SDS-PAGE to reassess the relationships of 27 samples represent six North American species and eight Old World species of Lupinus in the light of their chromosome counts and pervious taxonomic treatments. The relationships among the examined samples have been demonstrated as UPGMA and Neighbor joining (NJ) trees that agree with the taxonomy and ecogeographic distribution of the studied species. In both trees the 27 samples have been divided in two major groups; one small group comprised of the New World species and a large group comprised of the Old World species. The North American lupines are clearly delimited as separate identities with high levels of dissimilarity between them particularly in the UPGMA tree. In the NJ tree high levels of dissimilarity are observed between L. sativus and L. sylvestris and a cluster comprised of L. mutabilis, L. succulentus, L. elegans and L. hartwegii. The relationships among the Old World species, with few exceptions, correlate well with their morphology and intercrossing data. The morphologically diverse and genetically well-differentiated smooth-seeded species were separated as one group from the morphologically homogeneous and genetically less differentiated rough-seeded lupines. In the smooth seeded lupines, the separation of L. albus (2n=50) and L. angustifolius (2n=40) is congruent with their sectional delimitation, However, L. micranthus, (sect. Micranthi) and L. luteus and L. hispanicus (sect. Lutei) all have 2n=52. The rough seeded species are differentiated into two clusters; one includes the three samples of L. consentinii (2n=32) and the other comprises the two samples of L. pilosus (2n=42) and atlanticus (2n=38).