Nanorobotics is an emerging field based on the principle of nanotechnology. It deals with design and construction of devices so as to alter their functioning at the atomic, molecular or cellular level. Dr. Robert Freitas has designed nanorobots like clottocytes, respirocytes and microbivores. These hypothetical nanorobots are very small in size which can easily travel into human body and perform their functions. These nanorobots are designed in such a way so as to perform functions under specific conditions inside a human body. These nanorobots act as artificial substitutes to blood. The clottocytes mimics the process of haemostasis. The respirocytes mimics the function of red blood cells of transporting oxygen and carbon dioxide to various tissues and cells of the body. The microbivore mimics the function of natural phagocytes, which is carrying out phagocytosis. This review paper will discuss how the recent advancements in nanorobotics have helped in designing of these nanorobots.