Different cell types under normal and diseased states constantly secrete numerous membrane vesicles including exosomes into extracellular space wkich can be isolated from various biological fluids and cell culture supernatants. Exosomal diameter ranges between 40-100 nm. In current research, exosomes are being exploited as biomarkers for pathological diagnosis and potential remedy against various disease conditions such as infections and autoimmune disorders. In cancer immunotherapy, exosomes have promisingly been employed due to the identical immunogenic antigens of exosomes produced by neoplastic cells and the originating tissues. Antigen-specific T-cell activation and immunomodulatory activity is observed to be performed by exosomes isolated from tumor and dendritic cells (DCs). However, more research is still required to uncover the realistic uses of exosomes, particularly as drug delivery tool in autoimmune diseases, cancers and diabetes.