Editors' Summary: Environmental law has invaded the world of real estate transactions. When federal or state governments come to collect the costs of cleaning up unsafe hazardous waste sites, as statutory and common law authorize them to do, they may well stop at the door of the current landowner. The desire to avoid hidden liabilities has made hazardous waste law required reading for prospective purchasers and security holders of commercial real estate. The authors, environmental lawyers who have counseled clients buying and selling real estate containing hazardous waste, outline the sources of landowner liability for hazardous waste pollution and suggest steps that will help commercial real estate purchasers avoid hazardous waste liability. They conclude that the emergence of new statutory and common law governing liability for toxic waste pollution has not made landowners more likely to be liabile, but has greatly magnified the scope of the potential liability. Some states have tried to address the problem with statutes requiring registration of hazardous waste sites on deeds, but the authors counsel prospective purchasers to take additional protective steps, ranging from consulting environmental counsel to considering alternatives to outright purchase of the land.