Photodynamic therapy (PDT) relies on the interaction of light, photosensitizer, and the presence of oxygen, leading to cytotoxicity to the tissue containing the photosensitizer. The tissue specificity of photosensitizer is thus one of the key factors in photodynamic therapy. The limited targeting capability of current photosensitizers that are in the clinical applications has led to the active development of the new generation of photosensitizer. Another approach-peptide conjugation-to enhance the tissue specificity of photosensitizers were reviewed. The cell penetrating peptides, vasculature targeting peptides, and peptides targeting cell surface receptors were reviewed. The current research indicates that the effectiveness of peptide conjugation to confer the tissue specificity to photosensitizers.