The authors intended to test the suitability of creatine level and/or certain criteria of lipid analysis in radiosensitive organs for an individual (i.e. considering biologic variations of radiosensitivity), qualitative and quantitative demonstration of an irradiation damage. It was found that creatine determination and several criteria of lipid peroxidation are not suitable for a biologic radiation dosimetry due to the absence of organ dependent, radiation dose dependent, and time dependent changes. The reasons are discussed.