5-ALA benzyl ester hydrochloride is a lipophilic prodrug derivative of 5-aminolevulinic acid (5-ALA), designed for improved cellular uptake compared to standard 5-ALA. It is used in photodynamic therapy (PDT) for cancer treatment, where it is converted intracellularly to 5-ALA and subsequently to protoporphyrin IX (PpIX), a photosensitizer. When exposed to specific wavelengths of light, PpIX generates reactive oxygen species that destroy cancer cells. It is particularly explored in the treatment of skin, bladder, and brain cancers due to its ability to accumulate selectively in malignant tissues. Also investigated for use in fluorescence-guided surgery, where it helps surgeons visualize tumor margins. Additionally, it has applications in dermatology for targeting actinic keratosis and other skin lesions. In research, it aids studies on heme biosynthesis in molecular biology and biochemistry, and serves as a precursor for synthesizing biomolecules involved in cellular respiration.