Incipiently named extracellular vesicles, exosomes are forming now a separate class of cellular mediators with important functions in physiological and pathological states. Their ability to transfer information between cells through encapsulation of proteins, nucleic acids and lipids for the preservation of the homeostatic equilibrium is translated also in pathological conditions. The recipient cells react to the reception of foreign molecules adjusting their molecular state according to the enclosed message. Cancer cells, in order to influence the microenvironment and facilitate the malignant expanding, exploit this intercellular trafficking. Immune cells are also producing exosomes that ensure the transportation of immune mediators and signaling molecules between cells. Current experimental attempts are concentrated on the adjustment of exosomes level for therapeutic purposes, enrolment of these vesicles as diagnosis or prognosis tools and also exosomes' use as drug delivery vehicles or immune stimulatory agents.