The mycelial culture of the fungus Aleuria aurantia (Fr.) Fuck., Ascomycetes was established both on solid as well as on liquid nutrient media acc. Oddoux with some modifications. The culture was run for 3 weeks. Three distinct developing phases of growth were observed. The yield of dried mycelial biomass was 2,5-5,0 g/l respectively. 30 g of liophilized mycelium was used as a starting material for metabolites isolation. Two polysaccharide fractions A and B have been isolated from the water extract of the mycelium by subsequent praecipitation with ethanol and further purification. Fraction A isolated with good yield (1,97%) proved to be a heteroglucan composed of glucose, galactose and mamnose. It also contained a peptidic part with leucine, glycine and glutamic acid as components. It was submitted to evaluation of its biological activity. This kind of polysaccharides has often a marked immunotropic activity.