The intracellular lipases of Mucor circinelloides and Mucor racemosus immobilised in situ as well as the extracellular lipase of Rhizopus nigricans in soluble form were applied to enzymatic hydrolysis of waste fats from oil and meat industry, waste sludge of fats from municipal and industrial sewage-treatment plants and waste water containing microemulsion of fats. The reaction of hydrolysis of plant and animal waste fats was carried out by two methods. The first one was a partial hydrolysis of acylglycerols to obtain mono- and diacylglycerols. The second variant was complete hydrolysis of fats to obtain glycerol and free fatty acids. It has been demonstrated that lipase of Rhizopus nigricans partly hydrolysed waste fats. The products of hydrolysis contained 35-45% mono- and diacylglycerols. These products may be used as emulsifier in the hydrolysis of fats. The yield of hydrolysis of waste fats by immobilised Mucor lipases was from 85 up to over 95%. Waste sludge of fats from municipal and industrial sewage contain 12-62% of free fatty acids. This kind of material was hydrolysed without an emulsifier but with the addition of calcium chloride. The yield of hydrolysis of acylglycerols was from 45 to 76%. The yield of hydrolysis of microemulsion of fats in waste water by immobilised Mucor lipases was from 80 up to over 95%. As the hydrolysis products contained free fatty acids, mono- and diacylglycerols, it was easy to make emulsions which could be utilised in anaerobic-aerobic processes.