A U.S. study was conducted to characterize leachates from hazardous waste land disposal sites and to assess the feasibility of formulating a multicompound synthetic leachate for liner testing. Leachate samples from thirteen hazardous waste disposal sites were analyzed for priority pollutant compounds, total cyanide, total organic carbon, chemical oxygen demand, and various physical parameters. The analytical data were evaluated to characterize the occurrence frequency and concentrations of detected constituents in the leachates. Conclusions were made regarding the feasibility of formulating a synthetic leachate based on the study data. Recommendations were made for approaches to representing constituents in a leachate formulation and for follow-on analytical programs which would more comprehensively characterize leachates and enlarge the organic constituent data base.