The ring opening of γ-butyrolactone with 1 mole of potassium phthalimide and the hydrolysis of the intermediate product gave 4-aminobutyric acid with an excellent yield. The condensation of 1 mole of potassium phthalimide with 2-bromo-4-butyrolactone gave a 2-phthalimidolactone which can also be opened by treatment with a second molecule of potassium phthalimide. This diphthalimido acid when hydrolyzed gave, with an excellent yield, 2,4-diaminobutyric acid dihydrochloride.