The mammographic appearance of the female breast is influenced by physiological changes related to normal ageing (menopause), endocrine dysfunction, or the combined effects of these factors. During the period from 1 October 1995 to 30 November 1996, mammographic screening was performed on 2356 females from a Budapest district and multiple benign breast lesions (MBBL) were diagnosed in 211 (8.94%) subjects. The hormonal background of this lesion was explored by measuring serum sex hormone levels (oestradiol (E2), progesterone, testosterone, prolactin, FSH and LH) on 40 subjects randomly selected from both Group A (women with involutional changes only) and Group B (patients with MBBL). Serum E2 levels were considerably, but not statistically significantly higher in patients with MBBL (102.2±40.2 vs 50.8±18.7 pmol/l), whereas the elevations of serum progesterone (2.29±0.4 vs 0.901±0.5 nmol/l, P=0.0325) and LH (64.3±9.4 vs 48.9±13.9 IU/l, P=0.0194) levels were statistically significant. In patients with MBBL, parallel histological studies revealed persistent lobules with cell atypia. Consequently, MBBL with distinct radiomorphological features may result from endocrine dysfunction associated with the postmenopausal period. In such cases, cell atypia is more commonly diagnosed by histology. Accordingly, MBBL can be considered as a precancerous lesion. The changes in hormone levels observed suggest that endocrine dysfunction is accompanied by a slight impairment of negative feedback regulation, and regular clinical and laboratory screening of the risk population is