The question discussed in this paper is whether effective dose can reflect the risk to patients from radiological procedures and can be used, for example, to optimise procedures and compare risks of various methods, to define dose constraints, and to estimate the risks to individuals or populations attributed to medical exposures. This report demonstrates that the use of effective dose for patients could be misleading or even wrong due to inappropriate simplifications of the underlying biological mechanisms and inappropriateness of the weighting factors connected with the definition of effective dose for a given patient population. We show that the choice of the most meaningful quantities to express patient exposure depends strongly on the respective situation.