We have evaluated the psycho-social factors in women--during menopause with different biological characteristics--who participated in two extensive trials of breast cancer prevention: Diana1 and Tamoxifen. Through the use of a recognized personality test (MMPI, Minnesota Multiphasic Personality Inventory), we observed 500 healthy women who agreed to or refused the health care proposal. The findings show that the women who accept chemical preparations or to modify their dietary habits present different personality traits from those who refuse to adhere. One should ask oneself if the lack of homogeneity of the samples with a different concentration of psycho-social factors can alter the efficacy of a cancer prevention program. During chemoprevention studies, in which a high compliance could bring about a redundancy of experience of sickness, in coherence with our goal of health protection, we think it is necessary to supply psycho-social support which tempers any experience of physical, psychological and inter-personal discomfort in the healthy women. The cognitive model of the personality traits could be programmed also for the compliance of mammographical screening. This model requires the training of health care professionals.