Benefit/risk assessment (B/rA) can be used in a variety of circumstances encompassing clinical practice and research settings. Subsequent to the reporting of the results from the Breast Cancer Prevention Trial (BCPT), methodology was developed to perform B/rA for the use of the selected estrogen receptor modulator (SERM), tamoxifen. Although the methodology was specifically developed and applied to the use of tamoxifen, it is a generalized procedure that can be readily modified and applied to other forms of therapy including other SERMs. Recently, the methodology has been incorporated into the Study of Tamoxifen and Raloxifene (STAR) trial, a randomized clinical trial designed to compare the chemopreventive effects of two SERMs--tamoxifen and raloxifene. The B/rA of SERMs is complex because SERMs are known to exhibit properties that can reduce or increase the incidence of several health outcomes. This paper summarizes the uses of B/rA in the clinical practice and clinical trial settings and describes the constraints of the methodology as it is being applied to the assessment of therapy with SERMs.