The aim of the study was chemical analysis of polysaccharide fractions from sporocarps of <em>Sarcodon imbricatus</em> collected in natural sites and from the mycelium of <em>in vitro</em> cultures. Three polysaccharide fractions (F<sub>O</sub>I, F<sub>O</sub>II, F<sub>O</sub>III) were isolated from sporocarps and two (F<sub>K</sub>I, F<sub>K</sub>II) from <em>in vitro</em> cultures. Qualitative analysis by HPLC method showed that they are composed of galactose and fucose (F<sub>O</sub>I, F<sub>K</sub>I) or glucose and fucose (F<sub>O</sub>II, F<sub>K</sub>II). F<sub>O</sub>III fraction of the sporocarps consisted of glucose only. Molecular weights of isolated fractions ranged from 3.8 to 16.3 kDa for fractions from the sporocarps and from 5.8 to 14.7 kDa for that ones isolated from in vitro culture. The total percentage of sugar content for all fractions ranged from 97.8% to 99.1%. The percentage of uronic acids contents in acidic fractions was 2.6% and 2.7% for the FOI and FKI respectively. The work included also an assessment of cytotoxic activity of polysaccharide fractions in relation to tumor cell lines of human breast cancer MCV-7. FOI polysaccharide fraction of the sporocarps inhibited the growth of cancer cells in 50% compared to the control at a concentration of 0.0125%, while the polysaccharide fraction F<sub>K</sub>I from <em>in vitro</em> cultures inhibited cell growth in a concentration of 0.016%.