This paper introduces the effects of radiation quality with different ion species and various linear energy transfer on variable cell killing, remaining or initially measured breaks of G0/G1- prematurely condensed chromosome, mutation induction and deletion spectra in normal human fibroblasts. These results demonstrate that the LET-dependent structure is reflected in biological consequence of the repair process. Also, we indicate the possibility that the biological effects for different ion species are seen in not only a quantitative difference but also in a qualitative difference, in term of mutation induction. However, the importance of the biological effects caused by primary ions is still unclear in our irradiation systems, due to the use of polymethyl methacrylate absorbers of different thicknesses to change the energies of the ions. When considering the influence of galactic cosmic rays consists of high energy protons and heavy ions, it is important to further clarify the relationship between the different types of radiation and the effects
