[en] In heavy ion experiments, a large body of radiobiological data, (cross sections for cell inactivation and mutation, induction of both chromosome aberrations, and of strand breaks of DNA) has been measured for different atomic numbers, from helium (Z=2) to uranium (Z=92), and at energies between 1 and 1000 MeV/u which covers an LET range from 10 to 16000 keV/μm. These data exhibit a common feature: At LET values below 100 keV/μm all data points of one specific effect form one single curve as a function of LET, independent of the atomic number of the ion. In this LET range, the biological effects are independent from the particle energy or track structure and depend only on the energy transfer. Therefore, LET is a good parameter in this regime. For LET values greater than 100 keV/μm, the curves for the different ions separate from the common curve in order of increasing atomic numbers. In this regime LET is no longer a good parameter and the physical parameters of the formation of particle tracks are important. The similarity of the σ-LET curves for different endpoints shows that the 'hook-structure' is produced by physical and chemical effects which occur before the biologically relevant lesions are formed. For this part of the reaction chain only a very limited amount of data is available. This is especially true for the emission of delta electrons. There, the energy and angular distribution of the electrons and the positive deficiencies are required. The energy dependence of the production of chemical lesions should be known as well as their recombination probabilities. (orig.)