Twenty multiparous Holstein dry cows were divided randomly into four dietary groups differing in the dosage of chitosan supplementation being 0, 0.1, 0.2 and 0.3% of diet dry matter for the control, treatment I, II and III, respectively. Experimental diets were fed from 60 d before expected calving through 15 day in milk. Mean dry matter intake of each group cows was not significantly different (P>0.05). Chitosan increased (P<0.05) the concentrations of immunoglobulin (IgG, IgA and IgM) in the serum of dried cows after a feeding period of 60 days. It is suggested that chitosan could be used as an immunostimulant for dry dairy cows. Concentrations of glucose in plasma of group II and III were greater (P<0.05) than that of control and group I. Concentration of nonesterified fatty acids in experimental groups was significantly lower (P<0.05) than that of a control group. Supplementation of 0.2% chitosan significantly increased β-hydroxybutyric acid concentration in plasma.