We studied DNA interaction with caffeine and ions Mg2+ and Cu2+ in water solutions and dried films and influence of caffeine on DNA radiation damage. The main research methods were UV and IR-spectroscopy, UVCD, low gradient viscometry and atomic force microscopy. The results shows the caffeine-ions complexation, stronger with Cu2+ than with Mg2+. Addition of the third component to the DNA solution leads to the arising the DNA-caffeine-Me2+ complexes embracing the nitrogenous bases, which can be responsible for the prooxidant action. At the absence of divalent cations caffeine reveals the radioprotective action on DNA in solutions. In the presence of caffeine a decrease in the radiation effect on the DNA coil size in the solution, in the number of double-stranded breaks and damaged nitrogen bases, and in the degree of radiation-induced denaturation is observed.