Many women would like to after their breasts but are deterred by the risks involved. Silicone breast implants have been linked to a variety of illnesses, the most controversial of which are connective-tissue diseases. These circumstances urged us to perform this pilot study using a non-invasive method that involved the application of 17 beta-estradiol as it is known that estradiol enhances expression of insulin-like growth factor-I (IGF-I) which can promote growth in breast tissue. Forty-five women were included in the study. Their breast volume, IGF-I, prolactin (PRL) and estradiol levels were measured before treatment and between each application of 80 mg estradiol polyphosphate. The women's satisfaction with the results obtained was also subsequently evaluated. In 21 women (46.7%), breast size increased from 824.3 +/- 13.7 mm to 898.5 +/- 12.5 mm after 6 months. In these women a significant increase in IGF-I values was noted after 4 weeks of treatment. The increase in IGF-I values was not statistically significant in the remaining women. In addition, treatment was not successful in these women. IGF-I concentration seems to be of prognostic value as far as the response of breast tissue to estrogen stimulation is concerned. If IGF-I levels do not increase within 1 month, treatment should be discontinued. If IGF-I values do increase, this indicates that treatment is likely to be successful and can therefore be continued.