Many cell types secrete spherical membrane bodies classified as extracellular vesicles (EVs). EVs participate in intercellular communication and are present in body fluids, including blood, lymph, and cerebrospinal fluid. The time of EVs survival in the body varies depending on the body’s localisation. Once the EVs reach cells, they trigger a cellular response. Three main modes of direct interaction of EVs with a target cell were described: receptor-ligand interaction mode, a direct fusion of EVs with the cellular membrane and EVs internalisation. Studies focused on the medical application of EVs. Medical application of EVs may require modification of their surface and interior. EVs surface was modified by affecting the parental cells or by the direct amendment of isolated EVs. The interior modification involved introducing materials into the cells or direct administrating isolated EVs. EVs carry proteins, lipids, fragments of DNA, mRNA, microRNA (miRNA) and long non-coding RNA. Because of EVs availability in liquid biopsy, they are potential diagnostic markers. Modified EVs could enhance the treatment of diseases such as colorectal cancer, Parkinson’s disease, leukaemia or liver fibrosis. EVs have specific tissue tropisms, which makes them convenient organ-directed carriers of nucleic acids, drugs and vaccines. In conclusion, recently published works have shown that EVs could become biomarkers and modern vehicles of advanced drug forms.