Matching control selection strategies are often employed in PCOS case-control studies; however, they are infrequently used in an appropriate fashion. When properly applied, matching may offer improved study precision, but this is highly contingent on the causal pathway under consideration, strength of the associations between the matching variable and both the risk factor of interest and PCOS, and use of an appropriate stratified data analysis.Variations in design, including strategies to consider suspected confounding variables, may be in part responsible for discrepancies among study results reported in the polycystic ovary syndrome (PCOS) literature (1). The case-control study design is frequently used to consider hypothesized risk factors for PCOS, with investigators often complementing this framework with a 'matching' strategy in which controls are selected for cases according to the distribution of suspected confounding variables among the latter (2). A recent PubMed search (i.e., on 6/14/06), using the search terms 'polycystic ovary syndrome' and 'case-control studies', limited to the English language and 'published in the last 1 year', generated 40 citations, 23 of which fell under the PCOS case-control rubric. Almost half of these 23 studies, 11 (48%), matched controls to cases by body mass index (BMI), age, or both, but only one (9%) analyzed the data appropriately for its matched nature. In a prior publication, we discussed the merits of the case-control design for studies of PCOS causal risk factors (3); however, the proper