Lactase is an enzyme that breaks down the milk sugar lactose into glucose and galactose. It has attracted the attention of many researchers as it has a wide area of application in many industries. This enzyme can be produced from different sources such as bacteria, yeast and mould. Commercial lactases are produced from both yeasts and moulds. De-spite the fact that many techniques have been developed based on different microorganisms, there is still a need for alternative enzyme sources. For example, in dairy industry lactases that are stable in a wide pH and temperature range should be used. In this book, production of lactase from alternative fungal sources was studied. Aspergillus oryzae isolated from dairy effluents was screened for its ability to produce lactase production under solid state fermentation and the experimental results were discussed.