In this project, the effects of Ginkgo biloba L. leaf extract (GbLE) on the seed germination, seedling growth (radicle length, radicle number and fresh weight), mitotic activity and chromosomal aberrations of Allimn cepa L. germinated under both normal conditions and salt stress were studied. The radicle length of seeds germinated in the medium with GbLE alone increased in comparison with ones of the control seeds germinated in distilled water medium while their fresh weight reduced according to the control. However, the germination percentage and radicle number of the mentioned seeds were statistically the same as ones of the control seeds. Furthermore, the mitotic index and the frequency of chromosomal aberrations in root tip meristems of A. cepa seeds germinated in the medium with GbLE alone demonstrated a significant increase compared to the control seeds germinated in distilled water medium. On the other hand, salt stress considerably inhibited the seed germination and seedling growth of A. cepa. In addition, it markedly decreased the mitotic index in root tip meristems of the seeds and increased the number of chromosomal aberrations. Whereas, the inhibitive effect of salt on the seed germination, seedling growth and mitotic activity was dramatically alleviated in varying degrees by GbLE application. But, the detrimental effects of salt on the chromosomal aberrations greatly increased with this treatment.