Azolla commonly known as mosquitofern, duckweed fern, fairy moss, andwater fern, isa small free floating aquaticfernnative to Asia, Africa, and the America. It grows in swamps, ditches, and evenin lakesandrivers where the water is not turbulent (Lumpkin and Plucknett, 1980). The name Azolla is derived from thetwo Greek words, Azo (to dry) and Ollyo (tokill) thus reflecting that the fern is killed by drought. Azolla-Anabaena is a symbiotic complex in which the endophytic blue-green algae Anabaena zollae lives within the leaf cavities of the water fern Azolla (Lain). The endosymbiont, which is nitrogen-fixing, provides sufficient nitrogen for both itself and its host (Peters, 1978). The fern, on the other hand, provides aprotected environment for the algae and also supplies it with a fixed carbon source. It has capability to fix atmospheric nitrogen as well as to produce biomass at a very high rate. A lot of research works was done on azolla during the past and recent decades. The objective of this paper is to review and synthesize those research results with the hope that it will be helpful for collaborative research on this ‘green gold mine’ in future. Azolla is commonly used as biofertilizer as well as green manure in the paddy field. Now a days Azolla (either fresh or in dried) is alsoused as a feed ingredient for ruminants and nonruminants type of livestock. Besides its utilization as biofertilizer and livestock feed, azolla, the ‘green gold mine’ of the nature is also used as medicine, water purifier, human food and for production of biogas.