The comparative immunomodulatory effects of ${eta}$-glucans isolated from mushroom fungi (Coriolus versicol), yeast (Saccharomyces cerevisiae) and bacteria (Agrobacterium) on the major functions of macrophages were evaluated. As parameters of macrophage functions, we examined tumoricidal activity, phagocytosis, nitric oxide (NO) production, and the induction of inducible NO synthetase (iNOS) in RAW264.7 cells, following treatments with ${eta}$-glucans from the three different sources. The results indicated that all ${eta}$-glucan treatments significantly induced tumoricidal activity in the RAW264.7 cells, with a remarkable effect shown by the beta-glucan from Agrobacterium at a concentration of $10{mu}g/mL$. There was also a significant increase in iNOS-NO system activity in macrophages treated with ${eta}$-glucans extracted from yeast; however, iNOS-NO system activity was not markedly changed by the treatment of ${eta}$-glucans from C. versicolor mushroom fungi or Agrobacterium. Furthermore, the ${eta}$-glucans from C. versicolor had a significant phagocytotic effect at concentrations of 1, 10, and $100{mu}g/mL$. Taken together, the present data suggest that these ${eta}$-glucans, isolated from three different sources, have different effects on macrophage function, and therefore, may have different clinical uses in different for various types of diseases.