e"> In order to study the effective factors on the quality and quantity of lecithin extracted from soybean oil and the residual amount of phosphatids in degummed oil, this study was arranged. Crude oil recovered from soybean which had been processed by conventional solvent extraction and reached a phosphorus content of 454 ppm was used for this purpose. Treatments were carried out under different concentrations of phosphoric acid (zero, 0.05, 0.1, 0.2, 0.5, 2) and different percents of water ( 0.5, 1, 2, 5, 3, 4) at different temperatures (25, 50, 60, 75, 90 °C) and with different stirring times (5,10, 20, 40, 60 min). The highest phosphatid recovery was obtained with 3 %(v/v) water at 75 °C with a stirring time of 20 minutes. Adding phosphoric acid decreased the phosphatid residue in the degummed oil, but the quality of lecithin was reduced. However, the addition of phosphoric acid lower than 0.05 %(v /v) at 60 °C resulted in the same recovery efficiency with no major effect on the quality of lecithin.