Harmol is primarily used in research settings for its biological activity, particularly in studies related to fluorescence and cellular processes. It serves as a model compound in photobiological experiments due to its strong fluorescent properties, which help in tracing molecular interactions and dynamics within cells.

It has been investigated for its potential role in modulating enzyme activity, especially in relation to cytochrome P450 enzymes, making it useful in pharmacological studies on drug metabolism. Harmol also exhibits antimicrobial and antiparasitic properties, prompting exploration for use in developing treatments against certain pathogens.

Additionally, harmol is used in the study of DNA binding and intercalation, supporting research in cancer biology and the development of chemotherapeutic agents. Its ability to interact with nucleic acids and influence cell signaling pathways adds to its value in biochemical and biomedical research.