Ginkgo hiloba L., which was distributed in Korea, was x-rayed with 100, 250, 500, 1000, 2000, 6000R. The results of responses about germination, morphalogical variations in seedling and early stage growth may be summarized as follows : 1. The germination percent was decreased with X-ray increasing dose from 500R except the slight stimulation of 100R. 2. The germination LD an seemed to be 765R. 3. The seedling height was depressed significantly but only slightly in 100R. 4. The loaf index was increased proportionally to high dose but T/R ratio was reduced apparently. 5. The dry or fresh weight decreased from 250R. It was highly significant except 100R. 6. Many morphological variations were indicated in plants.