The effect of x-rays of various wave composition and intensity was investigated, as well as the effect of gamma rays on the electrical resistance of CdS monocrystals. The criterion, determining sensitivity, was a change in dark resistance in dependence upon the intensity and wave composition of the effective short wave radiation. The resistance was measured with a multirange line megometer. When a CdS crystal is used in the role of sensing element of gamma and x-ray dosimeter individual calibration is needed for each concrete case and for each sensing element. CdS sensitivity of the sensing element differs even for identical radiation dosages of various wave compositions.