Three novel diterpenoids, pseudolaric acids A, B and C, were isolated from the root bark of Pseudolarix kaempferi Gorden used as an antifungal agent in folk medicine in China. The structures of pseudolaric acids B and C were assigned as 1 and 6 by spectral and chemical evidence. Pseudolaric acids A, B and C possess antifungal activity and pseudolaric acid B possesses an antifertility effect.