Rapid advances in medicine and biotechnology resulted in the development of non-invasive diagnostic and prognostic biomarkers enabling convenient and accurate detection. Exosomes has recently emerged as non-invasive biomarker for a number of diseases including cancer. Exosomes are the small endosome originated membranous vesicles secreted in a number of biological fluids such as serum, saliva, urine, ascites, cerebrospinal fluid, etc. Exosomes contain microRNA proteins and mRNA which can be used as disease specific biomarkers. Here we reviewed recent advancement in the field of exosomes as diagnostic biomarker for cancer along with a brief overview of their biogenesis, function and isolation.