Two series of examinations were carried out in two voluntary test groups for the purpose of elucidating the correlation between ultraviolet light load and oxidative stress as well as the way it is influenced by nutritive radical scavengers. After a 6 to 7-hour impact of sunshine on the whole body (sunbathing beach) at n = 8 a continuous progredient increase of thiobarbituric acid reactive substances could be identified in the serum (from 5.56 +/- 0.98 to 8.91 +/- 0.99 mumol/l, p < 0.001), which after new exposure to sunshine reached 11.3 +/- 2.4 mumol/l. Likewise, a 15-minute exposure to ultraviolet light at n = 24 induced increases of TBRS concentrations lasting from 1-2 days. After 14-day supplementation with beta-carotene (n = 6), D-alpha-tocopherol (n = 6), selenium (n = 6), and ginkgo biloba extract (n = 6) the extent of the oxidative stress could be inhibited during a second exposure to ultraviolet light up to the following efficiency: Se > Ginkgo > beta-carotene > vitamin E. The clastogenous effect of sunshine and ultraviolet light must be regarded as a factor for initiating and promoting cancerogenesis in the total organism. Concerning the aetiopathogenesis of malignant melanoma the paramagnetic properties of free radicals with their nonenergetic effects of the magnetic field have to be considered more carefully in scientific examinations.