Botryosphaeran, an exopolysaccharide (EPS) of the (1→3);(1→6)-ß-D-glucan type, is produced by the ascomycete Botryosphaeria rhodina and was previously demonstrated to be non- mutagenic. The objective of this work was to evaluate the anti-mutagenic activity of botryosphaeran using the micronucleous test in mice, and also hypoglycaemic activity in rats with Diabetes mellitus type I, induced by streptozotocin (STZ). B. rhodina was grown on Vogel minimal salts medium with glucose (5 % w/v) as sole carbon source, for 72 h at 28˚C and shaken at 180 rpm. The extracellular fluid was treated with 3 volumes of absolute ethanol, and the resulting EPS precipitate resolubilised in water and dialyzed against deionised water, and freeze dried. Three solutions of different EPS concentrations (0.75; 1.5; 3.0 g/L) were used in the biological tests. The positive control group received 0.3 mL of sterilized saline solution via gavage, and the other group 0.3 mL of the lowest concentration of botryosphaeran solution plus an intra-peritoneal injection of cyclophosphamide (50 mg/kg body weight). After completing 30 h on the last day of treatment, all the animals were sacrificed, and the bone marrow cells of the femurs and peripheral blood collected for analysis. Hypoglycaemic activity was developed using a positive control group of rats that received STZ diluted in phosphate buffer solution (pH 4.5; 50 mg/kg bw) by intra-peritoneal injections. Forty eight h after injection, the rats were included in the diabetic groups, and the EPS solutions tested in subchronic assays. Botryosphaeran presented anti-mutagenic activity with all three EPS concentrations, 0.75; 1.5; 3.0 g/L, which reduced the micronucleous by 45, 71 and 78 %, respectively, in the bone marrow; and 45, 78 and 82 % in the peripheral blood. Botryosphaeran only showed 48 % hypoglycaemic activity using 3.0 g/L concentration.