Quantum Microscopy of Biological Systems This thesis reports on the development of the first quantum enhanced microscope and on its applications in biological microscopy. The first quantum particle tracking microscope described in detail here represents a pioneering advance in quantum microscopy which is shown to be a powerful and relevant technique for future applications in science and medicine. The microscope is used to perform the first quantum enhanced biological measurements a central and long standing goal in the field of quantum measurement. Subdiffraction limited quantum imaging is achieved also for the first time with a scanning probe imaging configuration allowing 10 nanometer resolution.