This paper studies the differences in perception of two radiological risks – an accident at a nuclear installation and medical X-rays – between four different groups: the general population without(1) and with experience related to radiological risks(2), new employees(3) and professionally exposed people(4) in the nuclear sector. This study determines if differences in risk perception can be explained by the level of experiences with ionizing radiation, the knowledge level about radiological risks, the confidence in authorities, the attitude towards nuclear energy, the trust in a management of nuclear installations, gender and age. The data are gathered using computer assisted personal interviews based on the SCK•CEN Barometer. The relations between risk perception and the independent variables are tested with linear regression analysis. The risk perception of both risks differs significantly. The professionally exposed people and the new employees in the nuclear sector have a significant higher risk perception for medical X-rays compared to the risk for an accident at a nuclear installation. For the general population without experience, it was just the opposite. Level of experiences with ionizing radiation is determined as an important variable; people have a lower perception of radiological risks when they have higher experiences with risk.