Background and aim: Glioblastoma multi pulmonary fibrosis is the most common malignant tumor of the central nervous system that occurs in the spinal cord or brain. Since Chemotherapy has many side effects in patient, todays the use of alternative natural ingredients in the direction of treatment expanded. The phycocyanin is a compound produced in cyanobacteria that has various properties, including anticancer properties. This study, in order to investigate the effects of Phycocyanin on the induction of apoptotic death on glioblastoma cell lineage. Materials and methods: Glioblastoma brain cell line (U87) was purchased from the cell bank of Iran Pasteur Institute, were cultured in RPMI 1640 medium containing 10 to 20% of the serum of fetal bovine animals and treated by Phycocyanin. Gene expression were investigated by means of real-time polymerase chain reaction. Results: The results of this study showed that phycocyanin has cytotoxic effects on glioblastoma cells and increases the expression level of caspase-8 gene. Conclusion: The present study showed that the phycocyanin had cytotoxic effects on glioblastoma cells and induces apoptosis via enhancing caspase-8 gene expression level.