A method for the production of fatty acid esters of primary and/or secondary alcohols from raw, unpurified oils or fats containing free fatty acids and slimy substances or from waste oils loaded with free fatty acids from the food industry. Acidic catalytic esterification is performed on the free fatty acids along with extensive deactivation of the slimy substances present with respect to the disadvantageous emulsion-forming property thereof, whereby a water-free primary and/or secondary alcohol and a highly acidic hygroscopic catalyst are added to the starting substance in the form of crude oil or fat or waste oil, the reaction product is rinsed with glycol from a prior alkaline transesterification, whereupon alkaline transesterification occurs for the unmodified remaining glyceridically bound fatty acids in the reaction product of the acidic-catalytic esterification process.