Marked differences in seedling vigor, as measured by dry weight two weeks after germination, have been demonstrated in F3 lines of a barley (Hordeum vulgare L. emend Lam.) cross between CI 5791 and Ming (CI 4797). These differences can be largely accounted for by differences in seed size, which is itself related to segregation for head type, and by differences in germination resistance. The latter character varies between cultivars and is itself influenced by seed size to some extent. It is concluded that, although seed size, directly and indirectly, can influence seedling vigor, inherent differences in this respect exist between barley cultivars. The significance of this is briefly considered.