The lipid content of microalgae varies among different species and strains (Table 2 [19,20]). The lipid content of microalgae is usually in the range of 20% to 50% (dry base), and can be as high as 80% under certain cir­cumstances. Selecting high lipid content and fast growing microalgae is an important step in the overall success of biodiesel production from mi­croalgae. Traditional methods of screening microalgae for high lipid con­tent rely on time-consuming and laborious lipid extraction process which involves cell wall disruption and solvent extraction of a reasonably large amount of microalgae cells. Recently, high-throughput screening tech­niques employing lipophilic fluorescent dye staining (such as Nile Red [21], BODIPY 505 [22]) and fluorescence microscopy or flow cytometry are being developed [23]. With these new techniques, the amount of sam­ple and preparation time are greatly reduced because the lipid content of algal cells is measured in situ without the need for extraction. Lipid con­tent and lipid productivity are two different concepts. The former refers to lipid concentration within the microalgae cells without consideration of the overall biomass production. However the latter takes into account both the lipid concentration within cells and the biomass produced by these cells. Therefore lipid productivity is a more reasonable indicator of a strain’s performance in terms of lipid production.