Trametes gibbosa, also referred to as lumpy bracket, is a fungus belonging to the Polyporaceae with natural bioactive compounds that have aroused great interest for their potential benefits in human health. This pilot study aimed to investigate the anti-cancer effect of Trametes gibbosa extract against the HCT-116 cell line (human colorectal cancer cells). The extract was obtained by macerating dry biomass with 3 solvents: acetone, isopropyl alcohol and DCM, isolating established anticancer agents –polysaccharide complexes (PSK and PSP) from the extract, and then being dissolved. Cellular toxicity was assessed by trypan blue staining, determining the effect of 1- and 24-hour continuous exposure to the extract of varying concentrations: 100 µl/mL, 200 µl/mL, 500 µl/mL, 1000 µl/ mL. Results have demonstrated a cytotoxic effect in time- and dose-dependent manners. The proposed cellular mechanisms behind the results are most likely apoptosis followed by secondary necrotic cell death, as the literature suggests, although that remains unclear and requires further experiments. Within the course of consecutive studies, it can be established whether the extract or the compounds contained may hold promise for clinical use, e.g., for adjuvant therapy.