A water insoluble β-glucan (PS), with molecular mass ∼9.16 × 10 Da was isolated from the 4% alkaline extract of an edible mushroom, Pleurotus djamor and found to consist of (1→3)-β-d-glucopyranosyl moiety. The structure of the PS was elucidated on the basis of total hydrolysis, methylation analysis, periodate oxidation, and NMR experiments (H, C, DQF-COSY, DEPT-135, and HSQC). The structure of the repeating unit of the polysaccharide was established as: →3)-β-d-Glcp-(1→. The water insoluble β-glucan showed cytotoxic effect against PA1 cells, where˜50% population was destroyed at 100 μg/mL concentration, and almost all cells at 250 μg/mL concentration. The wound healing assay showed significant anticarcinogenic effect against ovarian carcinoma PA1 cells after 48 h of treatment.