The probability to induce leukemia or malignoma by roentgenexamination of the gastrointestinal tract is quite small. Basing on riskestimations of the ICRP and own measurements, the probability is about 1:25,000 in angiography. For x-ray examination of the stomach-duodenum, the small bowl, and the colon the radiation risk is approximatively 1:300,000 to 1:800,000. The probability to provoque radiation induced mutations, manifesting themselves in future children or grandchildren, is quite similair for male patients. On the other hand the risk for future children and grandchildren of female patients is a bit higher. An exception is the roentgenexamination of the colon, because direct exposure of the testes is in general inevitable.