INTRODUCTION This is the fifteenth report on environmental protection expenditures of the petroleum industry within the United States prepared by the American Petroleum Institute's Environmental Affairs Department. The report summarizes environmental expenditures for air@ water@ land and other programs. Capital@ administrative@ operating and maintenance@ and research and development expenses are included. Expenses are also tabulated for each industry sector-exploration and production@ transportation@ marketing and manufacturing. The same format has been used for each survey so that annual expenditures for a specific reporting period can be readily compared with previous annual expenditures. However@ since the number of responding companies varied from survey to survey@ the reporting base for each may be slightly different. Expenditures listed are those actually reported to API rather than the industry's total expenditures. Partial expenditures have not been extrapolated to represent total industry expenditures. The report includes the percentages of refinery capacity represented by survey respondents during each of the ten years covered. The questionnaire used in the survey is found in Appendix A. The survey was developed after consultation with representatives of all petroleum industry disciplines. It is the same questionnaire used in previous API surveys. The questionnaire defines which expenses should be included or excluded and contains examples to assist in categorizing expense by industry sector and environmental media. The survey also includes guidelines for calculating expenditures on environmental activities. These guidelines cover all phases of industry operations and provide a uniform procedure for determining environmental expenditures. Although respondents were urged to report actual cost data@ in some cases it was necessary to estimate expenses. Questionnaires were submitted to the corporate offices of API members companies. Those companies which chose to participate in the survey reported environmental expenditures of more than $33 billion for the 10-year period ending in 1984. These companies represented@ in 1984@ approximately 82% of refining capacity of the U.S. petroleum industry. While this report contains information on environmental expenditures during 1975 to 1984@ it should be noted that the American Petroleum Institute has collected expenditure data since 1966. FigureI shows total environmental expenditures from 1967 to 1984. Detailed information on the distribution of these expenses can be found in the report for the appropriate period. A listing of reports from previous years is contained in Appendix B.