Abstract This study outlines the current state of expert system technology in environmental protection. The paper defines general characteristics of expert systems and identifies the kind of problems in environmental protection which are well suited for expert system use. This study introduces, classifies and briefly describes twenty-one expert system approaches from Canada and the F.R.G., many of them still in an early development state. The analysis and evaluation show that not many expert systems are in actual use for practical environmental decision making. Finally the areas with the highest potential for successful employment of today's expert system technology are identified and a number of research needs stated. More progress is needed towards truly operational, “intelligent” (i.e. AI-based) environmental information systems.