Corn samples included a commercial dent 1st-generation hybrid of 2 inbred lines (L289 X 1205) and an inbred line of sweet corn (P51). Seed packets were distributed in the target area at Bikini. Samples were exposed to the atomic bomb explosion. Other samples were exposed to x-rays. Doses of 5,000, 10,000, 15,000, 20,000, and 25,000 r were applied at the rate of 1,000 r/min. Ger-minability was not affected by the atomic bomb or by x-ray. Growth from the bombed sample nearest the target and from x-rayed samples treated with 10,000 and 15,000 r was retarded in the seedling stage. Sectors of defective tissue occurred in the older plants. The effects were accentuated by the heavier doses of x-rays. Morphological abnormalities occurred with about the same frequency, but chlorophyll-deficient sectors and sectors of dead tissue were much more frequent in the bombed sample than in the x-rayed sample. Reciprocal translocation was the most prevalent type of induced chromosomal alteration, the total number being 5 times the number of deletions and inversions. The same kinds of chromosomal changes were induced by the atomic bomb and x-rays. About 50% pollen abortion characterized most of the plants classed as having abnormal pollen. Radiations from the bomb produced effects comparable to those induced by 15,000 r of x-rays.