We studied the anti-arthritic activity of glucomannan (GM) isolated from Candida utilis and of Imunoglukán, a beta-(1,3/1,6)-D-glucan (IMG) isolated from Pleurotus ostreatus. Adjuvant arthritis (AA) was induced intradermally by the injection of Mycobacterium butyricum in incomplete Freund's adjuvant to Lewis rats. Blood for biochemical and immunological analysis was collected on experimental days 1, 14, 21, and 28. A clinical parameter--hind paw volume (HPV)--was also measured. The detection of IL-1 alpha, IL-4, TNF alpha, and MCP-1 was done by immunoflowcytometry. On day 28--the end of the experiment--we determined spectrophotometrically: the total anti-oxidant status (TAS) of plasma samples along with thiobarbituric acid-reacting substances (TBARS) levels in plasma and we assessed the activity of gamma-glutamyl transferase (GGT) in hind paw joint homogenate. The experiments included healthy animals, arthritic animals without treatment, and arthritic animals with administration of glucomannan (GM-AA) in the oral daily dose of 15 mg/kg b.w. and of IMG (IMG-AA) in the oral daily dose of 2 mg/kg b.w. The progress of AA was manifested by all parameters monitored. Both substances had beneficial effects on HPV, TBARS levels, GGT activity, and TAS levels. For cytokine assessment, only IMG-AA samples were selected, considering the significant HPV improvement accompanied with the observed anti-oxidant action. IMG administration had a positive immunomodulating effect on all cytokine plasma levels measured, changed markedly due to arthritis progression. Thus, IMG may be considered as a candidate for combinatorial therapy of rheumatoid arthritis.