The epidemiologic determinants of the mammographic pattern were studied in 710 patients with aspirated gross (> 1 ml) cysts of the breast. The prevalence of the mammograms classified as P2-DY, that are considered to be associated with an increased breast cancer risk, was 636/710 or 89.6%. No relationship between mammographic patterns and characteristics of breast cyst fluid such as K+/Na+ ratio, apocrine changes and dehydroepiandrosterone sulfate concentration was observed. A significant decrease in the proportion of these patterns with increasing age (p = 0.006), Quetelet Index (p < 0.001), parity (p = 0.001), and in postmenopausal women (p = 0.026) was found. Conversely, P2-DY patterns were significantly associated with a later age at menarche (p = 0.023) and alcohol consumption (p = 0.001). In multivariate analysis, an independent association with age was not observed whereas the associations with age at menarche, parity, and relative weight were confirmed. In conclusion, the epidemiologic determinants of mammographic patterns are the same in Gross Cystic Disease patients as in unaffected women, and the lack of correlation between mammographic pattern and cyst type suggests that the latter may represent an independent predictor of breast cancer risk.