INTRODUCTION Early in 1968@ the American Petroleum Institute's Committee for Air and Water Conservation directed a questionnaire to petroleum companies asking for data on their 1966 and 1967 pollution control expenditures in the United States@ and for projections of 1968 expenditures. Completed questionnaires were received from 35 of the 39 companies to which questionnaires were sent. These 35 companies process 97 per cent of all the crude oil refined in the United States. The data provided by the responding companies were compiled and interpreted for API by Crossley@ S-D Surveys@ Inc. Each questionnaire was treated as a confidential document and was returned to the sender when the compilation was completed.