This paper discusses many of the problems involved in making economically realistic appraisals of future U.S. and foreign oil discoveries. The old “discovery index” (DI) method (i.e., annual barrels new recoverable reserves added per foot exploratory drilling) can be modified to evaluate any country’s DI trends and to project when future oil discoveries may occur. The free world’s DI rate has been declining since 1969 at an average rate of 7% per year. In 30 years, new oil found may be at only 10% of today’s rate. Only the super oil-rich Persian Gulf region can count on having significant reserves of conventional oil thereafter. The end of our globe’s oil age will be in sight by 1999 and will effectively end during the first half of the twenty-first century.