(1→3)-β-D-Glucans exhibit a variety of biological and immunopharmacological activities, and the significance of these activities is dependent on the structure of the glucans such as molecular weight, degree of branching, and conformation. Based on the generally accepted evidence that the conformation of clinically used Sonifilan (SPG) is a triple helix, we prepared alkaline treated SPG (SPG-OH) as a single helix conformer. In this report, we examined (A) the antitumor effect on a solid form tumor in vivo, (B) hematopoietic response on cyclophosphamide induced leukopenia, (C) antagonistic effect for zymosan mediated-hydrogen peroxide synthesis on peritoneal macrophage (PM), (D) priming effect of lipopolysaccharide (LPS) triggered tumor necrosis factor (TNF) synthesis, (E) nitric oxide synthesis of PM in vivo, and (F) hydrogen peroxide synthesis of PM in vivo. Both SPG and SPG-OH showed a significant effect on (A) and (B). The activity on (C) was stronger in SPG than SPG-OH. The activities of (D), (E), and (F) were stronger in SPG-OH. These facts strongly suggested that the glucan-mediated immunopharmacological activities were dependent on the helical conformation, and the conformation dependency varied dependent on the assays used.