Abstract: Monoclonal antibody-based therapy has been a revolution in the therapy of both solid tumours and hematological malignancies. Continuous global efforts focusing on new strategies to improve therapeutic efficiency of antibodies by engineering second generation of antibodies fails to show much promise due to aggregation induced immunogenicity and their short half-life. Nanobodies are variable domain of heavy chain only antibodies. Conventional antibodies consist of two identical heavy (H) and two identical light (L) polypeptide chains (total four polypeptide chains) but camelids and some cartilaginous fish contains a unique form of immunoglobulin (IgG) without any light polypeptide chains and first constant domain (CH1) of heavy chain. Size of these unique antibodies ranges in nanometer therefore is popularly termed as nanobodies. The present article discussed the role of nanobodies in the therapy.