The selenium content of 518 specimens of rice, wheat, maize, soybean and highland barley growing both in Keshan disease area and other places in Yunnan Province, was determined and it was found that the average selenium content of the grains in the Keshan disease area was lower than that in the other places. The selenium content of rice especially was much lower than that of wheat and soybean. The relationship of Keshan disease to the low selenium content of grains, especially rice, the most eaten grain by people in the disease area, seemed clearly established in Yunnan province as well.