Purpose: This study aimed to evaluate the effect of intra-coronal bleaching after using C-Phycocyanin as a photosensitizing agent. Materials and methods: Fifty-one freshly extracted permanent anterior human teeth with intact crowns were used. All teeth were endodontically treated then stained with 2 mL of fresh rabbit blood and then centrifuged three times a day for 30 minutes. The teeth were randomly allocated according to the materials used for bleaching into group I (sodium perborate), group II (using C-Phycocyanin as a photosensitizer), and group III (control). The VITA easy shade V digital spectrophotometer was used for evaluation of the samples' color lightening parameter at baseline, at days 7 and 14 of the completion of the intracoronal bleaching procedure. Results: the sodium perborate treated group showed a significant increase in color lightening parameter at 7 and 14 days (P=0.048), while the C-Phycocyanin treated group showed a non-significant difference at 7 and 14 days (P=0.505). Conclusion: C-Phycocyanin had no satisfactory bleaching effect and is not a promising tooth-bleaching agent.