The effective dose (E) measures the stochastic risk of radiation exposure from the viewpoint of the induction of cancer and genetic diseases. In order to compare this risk in roentgen examinations, the effective dose was calculated for the most frequent roentgen examinations. The calculations were performed with a mathematical human phantom for a standard patient. Acquisition parameters were chosen according to national recommendations. The highest values were found for the small bowel enema and lumbar myelography, the lowest values for X-rays of the cervical spine, the paranasal sinuses and the upper thigh.