C-Phycocyanin (C-Pc) is one of the major biliprotein pigments of unicellular cyanbacterium of Spirulina platenesis, it has nutritional, medicinal, and hepatoprotectant application. The growth and multiplication of human hepatoma cell lines (HepG2) under the effect of different concentrations of C-PC (0.8, 1.75, 3.5 and 7.0 microg/ml) against untreated cells as control for 24h were investigated. The results showed that the proliferating cells in presence of C-PC reached 70, 51, 44, and 39%, respectively. The results revealed that the greatest reduction in proliferation of cells was recorded at 7.0 microg/ml and LC50 at 1.75 microg/ml of C-PC. In parallel, to the previous results HCl-denatured MG-P revealed that in mass of cells there is a pattern of apoptosis because the expanded cytoplasmic area (bluish-green) reduced and appeared faintly red as C-PC concentration increased. Moreover, the cells lost all the nuclear entities then, become fragmented and having no nuclear remnants. The C-PC may be a new potential anti-cancer drug for therapy of human hepatoma cells.