Abstract: A method is described for the determination of 227Ac in La2O3 by solvent extraction-liquid scintilation counting. The sample is dissolved with 2.5 N HNO3 and extracted by 5% HEHEHP-toluene, 227Ac being present in the aqueous phase The aqueous phase is allowed to stand for 5-15 days for the growth of 227Th. Then 227Th is extracted by HEHEHP (5%)-PPO (4.5g/l) -toluene and determined by liquid scintilation counting. The amounts of 227Ac in La2O3 can be calculated from the amounts of 227Th determined, The results indicate that this method is accurate and reliable and is less time and labor consuming than other methods.