Lichens are renowned for their ability to thrive in extreme environments and for producing unique metabolites with considerable bioactive potential. However, their medicinal value remains largely underexplored, primarily due to slow growth rates and habitat specificity. Notably, endolichenic microorganisms, particularly fungi, are the predominant producers of these bioactive compounds, which exhibit antimicrobial, antiviral, and anticancer properties. Investigating these microorganisms and their metabolites presents promising biomedical opportunities, underscoring the importance of sustainably utilizing lichen resources and discovering novel compounds. This paper reviews the diversity and bioactive potential of endophytic microorganisms in lichens, providing valuable insights for the exploration of natural resources. Keywords: Lichen; endophytes; secondary metabolites; biological activity; pharmaceutical potential.