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Phosphorus (P) is the eleventh most abundant element on Earth and is essential for life, but its presence in surplus quantities is problematic. Excessive P is responsible for eutrophication of water bodies which causes deterioration of aquatic environments, naturally and economically. Also, excess of P instigates operational problems for industrial facilities due to scale formation and accumulation, which may considerably hamper heat and mass transfer and translates into substantial financial loss. In many cases, the major component of the scale is a phosphate mineral (MgNH4PO4.6H2O), widely known as struvite. In contrast, due to its low solubility and its P content, struvite is an excellent fertilizer. The primary source of P is the phosphate rock, a non-renewable resource, of which about 80% is used as raw material for fertilizers. In line with increasing global population, demand for fertilizers increases rapidly, resulting in the dwindling availability of P world-wide. Thus serious attention is paid for P recovery and reuse. This paper focuses on P recovery from wastewater through crystallization of struvite. Firstly, a brief description of the theory of crystallization is presented. Then, basic research on crystallization of struvite is discussed. Finally, the different processes for P recovery as struvite are described.