A description is given of an improved process for the production of esters from fatty substances having a natural origin (animal and vegetable oils) and low molecular weight alcohols, in which the soaps and oily compounds entrained in the alkaline phases are recycled by treating them, following acidification and separation, with a fraction of the glycerol phase produced, in the presence of an alkaline catalyst and for forming preferably a triglyceride or a partly substituted glyceride.This process makes it possible to quantitatively obtain methyl, ethyl, propyl or butyl esters usable as a substitute for gas oil.