Abstract: With regard to study the effective factors on removal and quality 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 to a phosphorus content of 454 ppm, was used for this purpose. Treatment were carried out under different concentrations of phosphoric acid (0, 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 ¹) water at 75�C with stirring time of 20 min. Phosphoric acid adding decreased the phosphatid residue in degummed oil but the quality of lecithin was reduced. However addition of phosphoric acid lower than 0.05% (v v ¹) at 60�C resulted the same recovery efficiency without important effect on quality of lecithin.