Funds are requested to organize a meeting of investigators of all case-control studies of epithelial ovarian carcinoma conducted in the United States since 1974. The goals of this meeting are: to explore the feasibility of a collaborative analysis of the data sets produced by these studies; and if such an analysis is deemed feasible, to outline a plan for conducting it. Issues to be discussed include: criteria for including studies in the analysis; criteria for including subjects within a study; selection of variables to be examined; a common coding scheme for variables; reproducibility of histopathologic reports; and statistical methods. Among the potential benefits of a combined analysis are: new findings inaccessible to any one data set; new hypotheses about causal mechanisms for ovarian cancer that arise from ongoing discussions among the nation's most knowledgeable investigators; and new statistical methods for combining data sets with utility for other joint investigations of infrequently occurring chronic diseases. The low cost of conducting such an analysis compares favorably with its potential for increasing the value of data that has been collected at great cost.