Abstract: The free radicals of hairs from sufferer from different kinds of diseases except cancer have been systematially investigated by ESR. It is found that the diseases have also made great influence on I and P values of patient hair's free radicals. Therefore, it is not allowed simply to take the differences of I and P values between patient's hair and healthy person's hair with the same age as an evidence for judgement of cancer. The ESR measurements of 633 healthy people's hair show again that the statistic rule proposed by authors is valid, that is, the free radical concentration of human hair changes with growing age.

Key words: ESR parameter I and P, Free radical, Statistic rule