Zinc oxide nanostructures are interesting nanomaterials with a wide range of applications. Since the physical and chemical properties of ZnO nanoparticles are influenced both by their shape and size, a control of morphology of ZnO structures is needed for their commercial usage. Different chemical, physical, and biological methods used to produce ZnO nanostructures can be found in the literature. The production of ZnO nanoparticles using so-called green methods, using, for example, plant extracts or living organisms, is being investigated as these methods are environmentally friendly and of low-cost. This review also discusses the trends in the biological synthesis of semiconducting nanoparticles.