Anatomic indicators of increased breast cancer risk have regularly been identified as hyperplastic lesions, analogous to other body sites. Most of these have been shown to indicate a later increased risk anywhere in either breast and should thus be regarded as indicators or markers of increased risk. Unfortunately, these are largely identified incidentally to current methods of detection. Specific combined histologic and cytologic criteria for the definition of these lesions have been evaluated for both their reproducibility of diagnosis and outcome variables. Several studies agree that usual patterns of hyperplasia of at least moderate degree indicate an increased risk of later breast carcinoma between 1.5 and 2 times that of the general population. The specifically defined examples of atypical hyperplasia, lesions of relative rarity, are found in 4-5% of biopsies (depending upon method of detection) and recognize a risk in the range of 4-5 times that of the general population controlled for age and duration of follow-up. Thus, several cohort studies using comparable criteria for definition of the anatomic lesions have found similar clinical outcomes. Other approaches to histologic definition have produced a lesser degree of separation between the non "atypical" and other forms of hyperplasia. Although it is not clear whether we are dealing with continuous variables or discrete histologic/cytologic variables, it is clear that when combined criteria are used, a greater degree of predictability is obtained. Other related risk features include most predominantly family history, which when present with atypical hyperplasia indicates an increased risk beyond that of either alone. Other means of detection of these various lesions, such as fine needle aspiration cytology, have not been verified. True non-obligate precursors of breast cancer are probably confined to low grade and non-comedo ductal carcinomas of the breast.