The aim of our study is research of human hair under various conditions, study of irradiation, ozonization, and study of effects of some drugs on EPR spectral parameters. Samples were studied using X-Band EPR spectroscopic method, UV irradiation by mercury discharge lamp, ozonization by mixture of O2-O3. We have found the sensitivity of hair melanin to colorisation and decolorization of hairs. There is increase of free radical concentration on the melanine particles by irradiation of hairs. The long time of irradiation causes the degradation of melanin. Long term therapy using Condrosulf causes the change of melanin into pheomelanin, which shows EPR spectra with other spectral parameters. The changes of hair melanin correspond to the change of melanin in nails. The literature part about this topics is added.

        Key words: human hair, melanin, EPR spectroscopy, free radicals, ozone, diagnostics.