Further studies on the laminaran of Eisenia bicyclis, a brown alga belonging to the Laminariaceae were carried out. An average degree of polymerization of the laminaran was confirmed to be approximately 22. Smith degradation and methylation analysis also supported our previous conclusions that the laminaran was of a linear structure composed of β-1, 6- and β-1, 3-linked glucose residues without containing mannitol and at least the major portion of the 1, 6-linkages occurred as a block among the 1, 3-linked glucose residues. In contrast to the previous assumption, however, the proportion of 1, 6-linkages to 1, 3-ones appears to be roughly 1: 3.